INTRO TO NETWORKS [MIDTERM]
Why would a technician enter the command copy startup-config running-config?
To copy an existing configuration into RAM
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Which two commands would return you to the privileged EXEC prompt regardless of the configuration mode you are in? (Choose two.)
-CTRL+Z -end
What does the acronym CLI stand for? Describe and differentiate between the different means of accessing the Cisco CLI including the console port, Telnet, SSH, and the auxiliary port. [10,2]
-Command-Line Interface(cmd) Allows user to interact directly with the system in a test-based form. -Accessing Cisco CLI: Through the CLI/console port/SSH/Telnet A CLI-based network operating system (e.g., the Cisco IOS on a switch or router) enables a network technician to do the following: -Use a keyboard to run CLI-based network programs -Use a keyboard to enter text and text-based commands -View output on a monitor Console Port: This is a physical management port that provides out-of-band access to a Cisco device. Out-of-band access refers to access via a dedicated management channel that is used for device maintenance purposes only. The advantage of using a console port is that the device is accessible even if no networking services are configured, such as performing the initial configuration. A computer running terminal emulation software and a special console cable to connect to the device are required for a console connection. Telnet: Telnet is an insecure, in-band method of remotely establishing a CLI session, through a virtual interface, over a network. Unlike SSH, Telnet does not provide a secure, encrypted connection and should only be used in a lab environment. User authentication, passwords, and commands are sent over the network in plaintext. The best practice is to use SSH instead of Telnet. Cisco IOS includes both a Telnet server and Telnet client. SSH: SSH is an in-band and recommended method for remotely establishing a secure CLI connection, through a virtual interface, over a network. Unlike a console connection, SSH connections require active networking services on the device, including an active interface configured with an address. Most versions of Cisco IOS include an SSH server and an SSH client that can be used to establish SSH sessions with other devices. Auxiliary Port: Some devices, such as routers, may also support a legacy auxiliary port that was used to establish a CLI session remotely over a telephone connection using a modem. Similar to a console connection, the AUX port is out-of-band and does not require networking services to be configured or available.
Give a brief description of each of the following standards organizations: IEEE, IETF, EIA/TIA, IANA, and ISO. [18,3]
-Institute of Electrical and Electronics Engineers(IEEE) which is an organization that creates standards in many industries, including networking, healthcare, power and energy, and telecommunications. IEEE created the Ethernet and wireless 802.11 standard. -Internet Engineering Task Force(IETF) which is an organization that creates Request for Comments (RFC) documents to develop, update and maintain internet and TCP/IP Technologies. Electronic Industries Alliance(EIA) which is responsible for the standards related to the 19-inch racks to mount equipment, connectors, and electrical wiring. -Telecommunications Industry Association(TIA) is responsible for the standards of communication in radio equipment, cell towers, satellite communications, and VoIP devices. -Internet Assigned Numbers Authority(IANA) is responsible for managing IP address allocation, domain name management, and protocol identifiers for the Internet Corporation for Assigned names and Numbers (ICANN). -International Organization for Standardization(IOS) an international non-governmental organization made up of national standards bodies that develop and publish proprietary, industrial and commercial standards.
Which two devices are intermediary devices? (Choose two)
-Routers -Switches
Which two Internet connection options do not require that physical cables be run to the building? (Choose two.)
-Satellite -Cellular
What are two characteristics of a scalable network? (Choose two.)
-Suitable for modular devices that allow for expansion. -Grows in the size without impacting existing Users.
What is meant by the acronym ISP? Briefly discuss the different access technologies customers may use to connect to their ISP including cable, DSL, dial-up, satellite, and leased lines. [3,1]
-The acronym ISP is Internet Service Provider. This is a service from a company to allow users (home or business) to connect to the Internet. Examples companies include Xfinity, Verizon, AT&T, CenturyLink, Earthlink, just to name a few. Users can connect to the Internet using various devices such as a computer at home or work or through their smart device such as a smartphone, tablet or smart TV. Listed here are common ways to connect to the Internet: -Access through cable: Offered by cable TV service providers, the internet data signal transmits on the same cable that delivers cable TV. It provides a high bandwidth, high availability, and an always-on connection to the internet. -Access through DSL: Digital Subscriber Lines provide high bandwidth, high availability, and an always-on connection to the internet. DSL runs over a telephone line. -Access through dial-up: This is an inexpensive option that uses any phone line and a modem to connect to the Internet. The low bandwidth provided by a dial-up modem connection is not sufficient for large data transfer, although it is useful for mobile access while traveling. -Access through Cellular: Users access the Internet using a cell phone/tablet through the cellular network. Wherever you can get a cellular signal, you can get cellular internet access. Performance is limited by the capabilities of the phone and the cell tower to which it is connected. -Access through Satellite: This is a benefit in remote areas that would otherwise have no internet connectivity at all. Satellite dishes require a clear line of sight to the satellite. -Corporate connection options differ from home user options. Businesses may require higher bandwidth, dedicated bandwidth, and managed services. Connection options that are available differ depending on the type of service providers located nearby. Businesses may use dedicated leased Lines, which are reserved circuits within the service provider's network that connect geographically separated offices for private voice and/or data networking. The circuits are rented at a monthly or yearly rate.
Which two statements are true regarding the user EXEC mode? (Choose two.)
-The device prompt for this mode ends with > symbol. -Only some aspects of the router configuration can be viewed.
When a hostname is configured through the Cisco CLI, which three naming conventions are part of the guidelines? (Choose three.)
-The hostname should be fewer than 64 characters in length -The hostname should begin with a letter -The hostname should contain no spaces
Why are the pairs of wires in UTP cabling twisted together? What are some of the ways electronic signals on coppers wire can be degraded / distorted? [19,4]
-The wires are twisted together to cancel out the electromagnetic interference. The timing and voltage values of the electrical pulses are also susceptible to interference from two sources: Electromagnetic interference (EMI) or radio frequency interference (RFI) - EMI and RFI signals can distort and corrupt the data signals being carried by copper media. Potential sources of EMI and RFI include radio waves and electromagnetic devices, such as fluorescent lights or electric motors. Crosstalk - Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire. In telephone circuits, crosstalk can result in hearing part of another voice conversation from an adjacent circuit. Specifically, when an electrical current flows through a wire, it creates a small, circular magnetic field around the wire, which can be picked up by an adjacent wire.
What are two functions of end devices on a network? (Choose two.)
-They are the interface between humans and the communication network -They originate the data that flows through the network
Which command is used to back up the running-configuration file to the startup-configuration file? What are the effects of issuing the erase startup-config and reload commands? [7,2]
-To save changes made to the running configuration to the startup configuration file, use the copy running-config startup-config privileged EXEC mode command. -The startup config is removed by using the erase startup-config privileged EXEC mode command. After the command is issued, the switch will prompt you for confirmation. Press Enter to accept. This removed the current running configuration from NVRAM. -This is usually necessary when you've made unwanted changes to a device, and saved them. If you haven't saved any unwanted changes, you can simply issue a reload command from privileged EXEC mode to restore the start-up configuration.
Which option describes malicious code running on user devices?
-Virus -Worm -Trojan Horse
Compare and contrast the startup-config and running-config files by answering the following questions: -Where is each file physically located on a Cisco switch or router? -Which memory location is considered "volatile" and what does that mean? -Changes to which file will affect the immediate operation of that device? [8,2]
-startup-config - This is the saved configuration file that is stored in NVRAM(nonvolatile random-access memory). It contains all the commands that will be used by the device upon startup or reboot. Flash does not lose its contents when the device is powered off. -running-config - This is stored in Random Access Memory RAM (random-access memory) which is volatile. It reflects the current configuration. Modifying a running configuration affects the operation of a Cisco device immediately. RAM is volatile memory. It loses all of its content when the device is powered off or restarted.
Find the binary and hexadecimal equivalents of the following decimal numbers: 12, 67, and 240. Find the binary and decimal equivalents of the following hexadecimal numbers: F, 4C, and 3B. Convert the following IP address to its binary format: 172.16.45.123. [22,5]
12: Decimal Binary: 1100 Hexadecimal: C 67: Decimal Binary: 1000011 Hexadecimal: 43 240: Decimal Binary: 11110000 Hexadecimal: F0 F: Hexadecimal Binary: 1111 Decimal: 15 4C: Hexadecimal Binary: 01001100 Decimal: 76 3B: Hexadecimal Binary: 00111011 Decimal: 59 172.16.45.123: IP Address Binary: 10101100.10000.101101.1111011
Discuss the five levels of encapsulation from data, segment, packet, frame, and bits and include the type of addressing that may be used for that protocol data unit (PDU). Map each PDU to its corresponding layer in both the OSI model as well as the TCP/IP model. [16,3]
5 Levels of Encapsulation from Data: Encapsulation is the process where protocols add their information to the data. •At each stage of the process, a PDU has a different name to reflect its new functions. •There is no universal naming convention for PDUs, in this course, the PDUs are named according to the protocols of the TCP/IP suite. DATA The general term for the PDU used at the application layer SEGMENT -Transport Layer PDU -Segmenting is the process of breaking up messages into smaller units. Multiplexing is the processes of taking multiple streams of segmented data and interleaving them together. Segmenting messages has two primary benefits: •Increases speed - Large amounts of data can be sent over the network without tying up a communications link. •Increases efficiency - Only segments which fail to reach the destination need to be retransmitted, not the entire data stream. PACKET Network Layer PDU FRAME Data Link Layer PDU BITS Physical Layer PDU used when physically transmitting data over the medium **Sequencing messages is the process of numbering the segments so that the message may be reassembled at the destination. **TCP is responsible for sequencing the individual segments. **NOTE: If the Transport Header is TCP, then it is a segment. If the Transport Header is UDP then it is a datagram.
List the seven layers of the OSI Model in order and briefly describe the purpose of each layer. [14,3]
7 - Application The application layer contains protocols used for process-to-process communications. 6 - Presentation The presentation layer provides for common representation of the data transferred between application layer services. 5 - Session The session layer provides services to the presentation layer to organize its dialogue and to manage data exchange. 4 - Transport The transport layer defines services to segment, transfer, and reassemble the data for individual communications between the end devices. 3 - Network The network layer provides services to exchange the individual pieces of data over the network between identified end devices. 2 - Data Link The data link layer protocols describe methods for exchanging data frames between devices over a common media 1 - Physical The physical layer protocols describe the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for a bit transmission to and from a network device. **Note: Whereas the TCP/IP model layers are referred to only by name, the seven OSI model layers are more often referred to by number rather than by name. For instance, the physical layer is referred to as Layer 1 of the OSI model, data link layer is Layer2, and so on.
In which scenario would the use of a WISP be recommended?
A farm in a rural area without wired broadband access.
Which device performs the function of determining the path that messages should take through internetworks?
A router
Which feature describes using personal tools to access information and communicate across a business or campus network?
BYOD
How does BYOD change the way in which businesses implement networks?
BYOD provides flexibility in where and how users can access network resources.
Which access method would be the most appropriate if you call your manager to tell him you cannot access your router in another city over the internet and he provides you with the information to access the router through a telephone connection?
Aux
A large corporation has modified its network to allow users to access network resources from their personal laptops and smart phones. Which networking trend does this describe?
Bring your own device
Which feature contains options such as Public, Private, Custom and Hybrid?
Cloud Computing
Which access method would be most appropriate if you were in the equipment room with a new switch that needs to be configured?
Console
Which access method would be most appropriate if your manager gave you a special cable and told you to use it to configure the switch?
Console
Compare CSMA/CA used in IEEE 802.11 wireless networks to CSMA/CD in IEEE 802.3 wired Ethernet half duplex environments? [25,6]
Contention-Based Access - CSMA/CD •Used by legacy Ethernet LANs. •Operates in half-duplex mode where only one device sends or receives at a time. •Uses a collision detection process to govern when a device can send and what happens if multiple devices send at the same time. CSMA/CD collision detection process: •Devices transmitting simultaneously will result in a signal collision on the shared media. •Devices detect the collision. •Devices wait a random period of time and retransmit data. _______________________________________________________ Contention-Based Access - CSMA/CA •Used by IEEE 802.11 WLANs. •Operates in half-duplex mode where only one device sends or receives at a time. •Uses a collision avoidance process to govern when a device can send and what happens if multiple devices send at the same time. CSMA/CA collision avoidance process: •When transmitting, devices also include the time duration needed for the transmission. •Other devices on the shared medium receive the time duration information and know how long the medium will be unavailable.
What does the acronym "DHCP" stand for? What purpose does it serve and how do you configure a computer to make use of it? What is the purpose of the "ipconfig" command and what kind of device can it be used on? Why would you issue the "ping" command? [12,2]
DHCP: Dynamic Host Configuration Protocol. -DHCP enables automatic IPv4 address configuration for every end device that is DHCP-enabled. -To configure DHCP on a Windows PC, open the Control Panel > Network Sharing Center > Change adapter settings and choose the adapter. Next right-click and select Properties to display the Local Area Connection Properties. Next, click Properties to open the Internet Protocol Version 4 (TCP/IPv4) Properties window, then select Obtain an IP address automatically and Obtain DNS server address automatically. -Note: IPv6 uses DHCPv6 and SLAAC (Stateless Address Autoconfiguration) for dynamic address allocation. ipconfig: It is possible to display the IP configuration settings on a Windows PC by using the ipconfig command at the command prompt. The output will show the IPv4 address, subnet mask, and gateway information received from the DHCP server. -Used on a PC or switches. -The ping command can be used to test connectivity to another device on the network or a website on the internet.
Which attack slows down or crashes equipment and programs?
Denial of Service (DoS)
Which network infrastructure provides access to users and end devices in a small geographical area, which is typically a network in a department in an enterprise, a home, or small business?
LAN
Differentiate between full and half duplex operation. What makes an Ethernet switch preferable to an Ethernet hub? [24,6]
Duplex mode is the way or the direction of data transmission between two devices over the network into a LAN. In a LAN topology we have two modes of duplex. Half duplex communication and full duplex communication. Half duplex communication two devices can send and receive at a time but impossible to do it simultaneously while in a full duplex the devices can send and receive on the shared media simultaneously. Full duplex makes Ethernet switch is preferable than the Ethernet hub, because that allows us to save time by doing it simultaneously and make it more efficiently.
List and describe the fields included in an Ethernet frame. What are the minimum and maximum Ethernet frame sizes as defined by the IEEE 802.3 standard? [27,7]
Ethernet Frame Fields -Ethernet operates in the data link layer and the physical layer. •The minimum Ethernet frame size is 64 bytes and the maximum is 1518 bytes. The preamble field is not included when describing the size of the frame. •Any frame less than 64 bytes in length is considered a "collision fragment" or "runt frame" and is automatically discarded. Frames with more than 1500 bytes of data are considered "jumbo" or "baby giant frames". •If the size of a transmitted frame is less than the minimum, or greater than the maximum, the receiving device drops the frame. Dropped frames are likely to be the result of collisions or other unwanted signals. They are considered invalid. Jumbo frames are usually supported by most Fast Ethernet and Gigabit Ethernet switches and NICs.
Discuss the format and structure of an Ethernet MAC address. What does a broadcast MAC address look like? What will a host on an Ethernet network do if it receives a frame with a destination MAC address that does not match its own MAC address? [26,7]
Ethernet MAC Address -•In an Ethernet LAN, every network device is connected to the same, shared media. MAC addressing provides a method for device identification at the data link layer of the OSI model. -•An Ethernet MAC address is a 48-bit address expressed using 12 hexadecimal digits. Because a byte equals 8 bits, we can also say that a MAC address is 6 bytes in length. -•All MAC addresses must be unique to the Ethernet device or Ethernet interface. To ensure this, all vendors that sell Ethernet devices must register with the IEEE to obtain a unique 6 hexadecimal (i.e., 24-bit or 3-byte) code called the organizationally unique identifier (OUI). -•An Ethernet MAC address consists of a 6 hexadecimal vendor OUI code followed by a 6 hexadecimal vendor-assigned value. Broadcast MAC Address -An Ethernet broadcast frame is received and processed by every device on the Ethernet LAN. The features of an Ethernet broadcast are as follows: -It has a destination MAC address of FF-FF-FF-FF-FF-FF in hexadecimal (48 ones in binary). -It is flooded out all Ethernet switch ports except the incoming port. It is not forwarded by a router. -If the encapsulated data is an IPv4 broadcast packet, this means the packet contains a destination IPv4 address that has all ones (1s) in the host portion. This numbering in the address means that all hosts on that local network (broadcast domain) will receive and process the packet. Destination MAC Address does not match its own. -The device discards the Frame.
Which network infrastructure might an organization use to provide secure and safe access to individuals who work for a different organization but require access to the organization's data?
Extranet
Which term refers to a network that provides secure access to the corporate offices by suppliers, customers and collaborators?
Extranet
What are the advantages and disadvantages of using fiber optic cabling versus copper cabling? Give specific examples where each type of cabling may be best used. [20,4]
FIBER OPTIC BEST USED -Commonly Used to Interconnect Network Devices. -Fiber-optic cabling is now being used in four types of industry: -Enterprise Networks - Used for backbone cabling applications and interconnecting infrastructure devices -Fiber-to-the-Home (FTTH) - Used to provide always-on broadband services to homes and small businesses -Long-Haul Networks - Used by service providers to connect countries and cities -Submarine Cable Networks - Used to provide reliable high-speed, high-capacity solutions capable of surviving in harsh undersea environments at up to transoceanic distances. Search the internet for "submarine cables telegeography map" to view various maps online. -optical fiber is primarily used as backbone cabling for high-traffic, point-to-point connections between data distribution facilities ADVANTAGES -Nobody can eavesdrop over fiber optic cabling -Transmit Data over Longer Distances -Higher Bandwidth -Less Attenuation Completely Immune to EMI and RFI. DISADVANTAGES -Flexible, but Extremely Thin, Transparent Strand of Very Pure Glass. -More expensive -More Installation Skill -Highest Safety Precautions COPPER BEST USED -Copper cabling is the most common type of cabling used in networks today. In fact, copper cabling is not just one type of cable. There are three different types of copper cabling UTP, STP, Coaxial Cable. -Generally used for interconnecting network hosts with intermediary networking devices, such as switches and routers. ADVANTAGES -Inexpensive -Easy to Install -Low Resistance to Electrical Current DISADVANTAGES -Limited by Distance -Signal Interference -EMI and RFI signals can distort and corrupt the data signals being carried by copper media. Potential sources of EMI and RFI include radio waves and electromagnetic devices, such as fluorescent lights or electric motors. - Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire. In telephone circuits, crosstalk can result in hearing part of another voice conversation from an adjacent circuit. Specifically, when an electrical current flows through a wire, it creates a small, circular magnetic field around the wire, which can be picked up by an adjacent wire.
A college is building a new dormitory on its campus. Workers are digging in the ground to install a new water pipe for the dormitory. A worker accidentally damages a fiber optic cable that connects two of the existing dormitories to the campus data center. Although the cable has been cut, students in the dormitories only experience a very short interruption of network services. What characteristic of the network is shown here?
Fault Tolerance
Having multiple paths to a destination is known as redundancy. This is an example of which characteristic of network architecture?
Fault Tolerance
Describe the four basic characteristics we strive to attain in today's networks: fault tolerance, scalability, quality of service (QoS), and security. [5,1]
Fault Tolerance: This is a network that limits the number of affected devices during a failure. Essentially a fault tolerance acts as a recovery to allow alternative paths to be sent around the network if the mainline fails. This ensures that the user experience is not affected if such an event were to occur. Think of it almost as a Network "backup." Scalability: A scalable network expands to support new users and applications. It allows a new network to be added to the existing network without degrading the user experience. Scalable networks allow designers to follow accepted standards and protocols to 'scale' the network's capability. Letting software and hardware vendors focus on improving products and services without having to design a whole new set of rules for operating within the network. Quality of Service (QoS): Quality of Service is a huge requirement in today's networking field. It is a primary mechanism for managing congestion. For example, when various messages are being sent across the network, the demand for network bandwidth can eventually exceed its availability, causing network congestion. Quality of Service is to ensure reliable delivery of content to all its users. The importance of Quality of Service is to prioritize time-sensitive traffic. Managed by the router, ensures that priorities are matched with with the type of communication and its importance to the organization. Network Security: -Network security is managed by the network administrators. Network administrators must address two types of network security concerns: -Network infrastructure security -Information security. -Administrators must protect information contained within the packets being transmitted across the network and information that is stored on the network that attaches to devices. -Securing the network infrastructure involves preventing unauthorized access to the management software that also resides on them. In order to achieve the goals of network security, there are three primary requirements: -Confidentiality - Data confidentiality means that only the intended and authorized recipients can access and read data. -Integrity - Data integrity assures users that the information has not been altered in transmission, from origin to destination. -Availability - Data availability assures users of timely and reliable access to data services for authorized users.
When data is encoded as pulses of light, which media is being used to transmit the data?
Fiber-Optic Cable
Which option blocks unauthorized access to your network?
Firewall
Which IOS mode are you in if the Switch(config)# prompt is displayed?
Global Configuration Mode
Describe the difference between a host/end device and an intermediary device. Give examples of each. [2,1]
HOST/END -Each end device on a network has an address. -When an end device initiates communication, it uses the address of the destination end device to specify where to deliver the message. -An end device is either the source or destination of a message transmitted over the network. -All computers that are connected to a network and participate directly in network communication are classified as hosts. -Hosts can be called end devices or clients. -Specifically hosts refer to devices on the network that are assigned a number for communication purposes. -Desktop -Labtop -Phones -Server -Printer INTERMEDIARY -Connects the individual end devices to the network. -They use the destination end device address -Determine the path that messages should take through the network. -They can connect multiple individual networks to form an internetwork Intermediary network devices perform some or all of these functions: -Regenerate and retransmit communication signals -Maintain information about what pathways exist through the network and internetwork -Notify other devices of errors and communication failures -Direct data along alternate pathways when there is a link failure -Classify and direct messages according to priorities -Permit or deny the flow of data, based on security settings **Note: Not shown in legacy Ethernet hub. An Ethernet hub is also known as a multiport repeater. Repeaters regenerate and retransmit communication signals. Notice that all intermediary devices perform the function of a repeater. -Wireless Routers -Multilayer Switch -LAN Switch -Firewall Appliance -Router
Which of the following is the name for all computers connected to a network that participate directly in network communication?
Hosts
Which connections are specialized ports on a networking device that connect to individual networks?
Interface
Which statement is true about the running configuration file in a Cisco IOS device?
It affects the operation of the device immediately when modified.
What is the function of the shell in an OS?
It interfaces between the users and the kernel.
What is an ISP?
It is an organization that enables individuals and businesses to connect to the Internet.
What is the Internet?
It provides connections through interconnected global networks.
Describe the following terms: LAN, WAN, intranet, extranet, and Internet. [4,1]
LAN A LAN is a network infrastructure that spans a small geographical area. LANs have specific characteristics: -LANs interconnect end devices in a limited area such as a home, school, office building, or campus. -A LAN is usually administered by a single organization or individual. Administrative control is enforced at the network level and governs the security and access control policies. -LANs provide high-speed bandwidth to internal end devices and intermediary devices. WAN -A WAN is a network infrastructure that spans a wide geographical area. WANs are typically managed by service providers (SPs) or Internet Service Providers (ISPs). WANs have specific characteristics: -WANs interconnect LANs over wide geographical areas such as between cities, states, provinces, countries, or continents. -WANs are usually administered by multiple service providers. -WANs typically provide slower speed links between LANs. INTRANET -Similar to the term Internet -Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organization. An intranet is designed to be accessible only by the organization's members, employees, or others with authorization. EXTRANET -Similar to the term Internet -An organization may use an extranet to provide secure and safe access to individuals who work for a different organization but require access to the organization's data. Here are some examples of extranets: -A company that is providing access to outside suppliers and contractors -A hospital that is providing a booking system to doctors so they can make appointments for their patients -A local office of education that is providing budget and personnel information to the schools in its district INTERNET -The internet is a worldwide collection of interconnected networks (internetworks, or internet for short). -The internet is not owned by any individual or group. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and standards as well as the cooperation of many network administration agencies. There are organizations that were developed to help maintain the structure and standardization of internet protocols and processes. These organizations include the Internet Engineering Task Force (IETF), Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), plus many others.
Briefly explain the limitations of wireless communications. What are some of the advantages of using wireless or wired media? What devices on the network are typically wired and which type of devices are increasingly becoming wireless? [21,4]
LIMITATIONS -Coverage area - Wireless data communication technologies work well in open environments. However, certain construction materials used in buildings and structures, and the local terrain, will limit the effective coverage. -Interference - Wireless is susceptible to interference and can be disrupted by such common devices as household cordless phones, some types of fluorescent lights, microwave ovens, and other wireless communications. -Security - Wireless communication coverage requires no access to a physical strand of media. Therefore, devices and users, not authorized for access to the network, can gain access to the transmission. Network security is a major component of wireless network administration. -Shared medium - WLANs operate in half-duplex, which means only one device can send or receive at a time. The wireless medium is shared amongst all wireless users. Many users accessing the WLAN simultaneously results in reduced bandwidth for each user. ADVANTAGES -Greatest Mobility -Immune to Electrical Hazards EMI & RFI -It Travels the Farthest Maintaining the Highest Bandwidth. -Cheaper WIRED -Routers -Switches [Using Copper or Fiber Cables] WIRELESS -Phones -Labtops -Headphones -Bluetooth
Which type of network topology lets you see which end devices are connected to which intermediary devices and what media is being used?
Logical Topology
Which type of network topology lets you see the actual location of intermediary devices and cable installation?
Physical Topology
Which connection physically connects the end device to the network?
NIC
An administrator has just changed the IP address of an interface on an IOS device. What else must be done in order to apply those changes to the device?
Nothing must be done. Changes to the configuration on an IOS device take effect as soon as the command is typed correctly and the Enter key has been pressed.
Explain the difference between a client-server network and a peer-to-peer network. What are the advantages and disadvantages of a peer-to-peer network? [1,1]
PEER-TO-PEER Advantages -Easy to set up -Less complex -Lower cost because network devices and dedicated servers may not be required. -Can be used for simple tasks such as transferring files and sharing printers Disadvantages -No centralized administration -Not as secure -Not scalable -All devices may act as both clients and servers which can slow their performance. CLIENT-SERVER -In a client-server network or application, you typically will have one or more high-end computers (servers) whose operating systems and applications are specifically tuned to answer simultaneous requests from large numbers of devices on the network. Computers or the applications on them making the requests are called clients. A good example of this is a user using a web browser such as Google Chrome on their laptop (the client) accessing a web site hosted on a Linux server running Apache web services (the server). Web services, email, file services, database services, and directory/security services are good examples of client-server networking. -Client and server software usually run on separate computers, but it is also possible for one computer to be used for both roles at the same time. In small businesses and homes, many computers function as the servers and clients on the network but in a limited capacity. Think of a desktop computer that shares their printer or a folder of documents with other computers on the network. This type of network is called a peer-to-peer network.
What commands are used to password protect access to a switch or router's console port and VTY lines? What is the purpose of the enable secret password command?[6,2]
PROTECT ACCESS: SWITCH or ROUTER'S CONSOLE PORT Switch# configure terminal Switch(config)# line console 0 Switch(config-line)# password cisco Switch(config-line)# login Switch(config-line)# end PROTECT ACCESS: VTY LINES Switch# configure terminal Switch(config)# line vty 0 15 Switch(config-line)# password cisco Switch(config-line)# login Switch(config-line)# end ENABLE SECRET PASSWORD COMMAND -Require a password for entry into privilaged EXEC mode -Protects complete access to a device -After entering the enable command in user EXEC mode, the user will be prompted to enter the password. Switch# configure terminal Switch(config)# enable secret class Switch(config)# exit
Which feature is being used when connecting a device to the network using an electrical outlet?
Powerline
Which IOS mode allows access to all commands and features?
Privileged EXEC mode
What is a "protocol"? Describe the terms "segmentation" and "encapsulation". Describe the following message types: unicast, multicast, and broadcast. [13,3]
Protocol: Set of rules for formatting and processing data. It is a common language for computers to use. Computers within a network may use very different software and hardware, but the use of protocols enables them to communicate with each other regardless. Segmentation: The process of dividing a stream of data into smaller units for transmissions over the network. Segmentation is necessary because data networks use the TCP/IP protocol suite send data in individual IP packets. Each packet is sent separately, like sending a long letter as a series of individual postcards. Packets containing segments for the same destination can be sent over different paths. Encapsulation: During encapsulation, each succeeding layer encapsulates the PDU that it receives from the layer above in accordance with the protocol being used. At each stage of the process, a PDU has a different name to reflect its new functions. Although there is no universal naming convention for PDUs, in this course, the PDUs are named according to the protocols of the TCP/IP suite. Unicast: Is a delivery method used to transmit information to a single end device. Multicast: Is a delivery method used to transmit information to one or more end devices. Broadcast: Is a delivery method used to transmit information to one or all end devices.
With which type of policy, a router can manage the flow of data and voice traffic, giving priority to voice communications if the network experiences congestion?
QoS
Which memory location on a Cisco router or switch will lose all content when the device is restarted?
RAM
Suppose computer A is sending a message to computer B which is on the same network as computer A. What layer 2 and 3 source and destination addresses will be used in the communication process? How would that be different if computer B was on a different network than computer A? [17,3]
SAME NETWORK -When the sender and receiver of the IP packet are on the same network, the data link frame is sent directly to the receiving device. On an Ethernet network, the data link addresses are known as Ethernet Media Access Control (MAC) addresses, as highlighted in the figure. -MAC addresses are physically embedded on the Ethernet NIC. -Source MAC address - This is the data link address, or the Ethernet MAC address, of the device that sends the data link frame with the encapsulated IP packet. The MAC address of the Ethernet NIC of PC1 is AA-AA-AA-AA-AA-AA, written in hexadecimal notation. -Destination MAC address - When the receiving device is on the same network as the sending device, this is the data link address of the receiving device. In this example, the destination MAC address is the MAC address of the FTP server: CC-CC-CC-CC-CC-CC, written in hexadecimal notation. DIFFERENT NETWORK -When the sender and receiver of the IP packet are on different networks, the Ethernet data link frame cannot be sent directly to the destination host because the host is not directly reachable in the network of the sender. The Ethernet frame must be sent to another device known as the router or default gateway. In our example, the default gateway is R1. R1 has an Ethernet data link address that is on the same network as PC1. This allows PC1 to reach the router directly. -Source MAC address - The Ethernet MAC address of the sending device, PC1. The MAC address of the Ethernet interface of PC1 is AA-AA-AA-AA-AA-A A. -Destination MAC address - When the receiving device, the destination IP address, is on a different network from the sending device, the sending device uses the Ethernet MAC address of the default gateway or router. In this example, the destination MAC address is the MAC address of the R1 Ethernet interface, 11-11-11-11-11-11. This is the interface that is attached to the same network as PC1, as shown in the figure. -The Ethernet frame with the encapsulated IP packet can now be transmitted to R1. R1 forwards the packet to the destination, Web Server. This may mean that R1 forwards the packet to another router or directly to Web Server if the destination is on a network connected to R1. -It is important that the IP address of the default gateway be configured on each host on the local network. All packets to a destination on remote networks are sent to the default gateway. Ethernet MAC addresses and the default gateway are discussed in more detail in other modules.
Discuss the difference between store-and-forward and cut-through switching methods. Which has more latency? What is the purpose of the auto-MDIX feature on a switch? [30,7]
Switches use one of the following forwarding methods for switching data between network ports: -Store-and-forward switching - This frame forwarding method receives the entire frame and computes the CRC. If the CRC is valid, the switch looks up the destination address, which determines the outgoing interface. Then the frame is forwarded out of the correct port. -Cut-through switching - This frame forwarding method forwards the frame before it is entirely received. At a minimum, the destination address of the frame must be read before the frame can be forwarded. Store-and-Forward Switching -A big advantage of store-and-forward switching is that it determines if a frame has errors before propagating the frame. When an error is detected in a frame, the switch discards the frame. Discarding frames with errors reduces the amount of bandwidth consumed by corrupt data. -Store-and-forward switching is required for quality of service (QoS) analysis on converged networks where frame classification for traffic prioritization is necessary. For example, voice over IP (VoIP) data streams need to have priority over web-browsing traffic. Cut-through-Switching In cut-through switching, the switch acts upon the data as soon as it is received, even if the transmission is not complete. The switch buffers just enough of the frame to read the destination MAC address so that it can determine to which port it should forward out the data. The switch does not perform any error checking on the frame. There are two variants of cut-through switching: -Fast-forward switching - Offers the lowest level of latency by immediately forwarding a packet after reading the destination address. Because fast-forward switching starts forwarding before the entire packet has been received, there may be times when packets are relayed with errors. The destination NIC discards the faulty packet upon receipt. Fast-forward switching is the typical cut-through method of switching. -Fragment-free switching - A compromise between the high latency and high integrity of store-and-forward switching and the low latency and reduced integrity of fast-forward switching, the switch stores and performs an error check on the first 64 bytes of the frame before forwarding. Because most network errors and collisions occur during the first 64 bytes, this ensures that a collision has not occurred before forwarding the frame. Auto-MDIX -Connections between devices once required the use of either a crossover or straight-through cable. The type of cable required depended on the type of interconnecting devices. **Note: A direct connection between a router and a host requires a cross-over connection. -Most switch devices now support the automatic medium-dependent interface crossover (auto-MDIX) feature. When enabled, the switch automatically detects the type of cable attached to the port and configures the interfaces accordingly. -The auto-MDIX feature is enabled by default on switches running Cisco IOS Release 12.2(18)SE or later. However, the feature could be disabled. For this reason, you should always use the correct cable type and not rely on the auto-MDIX feature. -Auto-MDIX can be re-enabled using the mdix auto interface configuration command.
What characteristic of a network enables it to quickly grow to support new users and applications without impacting the performance of the service being delivered to existing users?
Scalability
When designers follow accepted standards and protocols, which of the four basic characteristics of network architecture is achieved?
Scalability
Confidentiality, integrity, and availability are requirements of which of the four basic characteristics of network architecture?
Security
During a routine inspection, a technician discovered that software that was installed on a computer was secretly collecting data about websites that were visited by users of the computer. Which type of threat is affecting this computer?
Spyware
What type of interface has no physical port associated with it?
Switch Virtual Interface (SVI)
What do the following hot keys and shortcuts do: Tab, Enter Key, Space Bar, Ctrl-Z, up and down arrows, Ctrl-Shift-6, and Ctrl-C? Typing the "?" while using the CLI will do what? [11,2]
Tab: Finishes the partial command. Enter Key: Displays the next line. Space Bar: Displays the next screen. Ctrl-Z: When in any configuration mode, it will bump you back down a level to privileged EXEC mode. Up & Down Arrows: Up Arrow or Ctrl+P - Recalls the most recent command used. Down Arrow or Ctrl+N - Goes to the next line in the history buffer. Ctrl-Shift-6: All-Purpose break sequence used to abort DNS lookups, traceroutes, pings, etc. Ctrl-C: When in any configuration mode, ends the configuration mode and returns to privileged EXEC mode. When in setup mode, aborts back to the command prompt. ? while using the CLI: Displays a list of commands available for each command mode. You can also obtain a list of associated keywords and arguments for any command.
Which access method would be the most appropriate in-band access to the IOS over a network connection?
Telnet/SSH
What type of network must a home user access in order to do online shopping?
The Internet
List the four layers of the TCP/IP model and identify the equivalent layer(s) of the OSI model. Also, identify the commonly used protocols found at each of the four layers of the TCP/IP Protocol Suite. [15,3]
The TCP/IP Layer 4 or the Application Layer is equivalent to the Layer 7 - Application, Layer 6 - Presentation and Layer 5 - Session Layers of the OSI Model. The protocols in the TCP/IP Application layer are HTTP, DNS, DHCP, FTP. The TCP/IP Layer 3 or the Transport Layer is equivalent to the Layer 4 - Transport Layer of the OSI Model. The protocols in the TCP/IP Transport layer are TCP, UDP. The TCP/IP Layer 2 or the Internet Layer is equivalent to the Layer 3 - Network Layer of the OSI Model. The protocols in the TCP/IP Internet layer are IPv4, IPv6, ICMPv4, ICMPv6. The TCP/IP Layer 1 or the Network Access Layer is equivalent to the Layer 2 - Data Link and Layer 1 - Physical Layer of the OSI Model. The protocols in the Network Access layer are Ethernet, WLAN, SONET, SDH.
Briefly discuss the following WAN topologies: point-to-point, hub and spoke, and mesh (full/partial). Briefly discuss the following LAN topologies: bus, ring, star, extended star. [23,6]
There are three common physical WAN topologies: •Point-to-point - the simplest and most common WAN topology. Consists of a permanent link between two endpoints. •Hub and spoke - similar to a star topology where a central site interconnects branch sites through point-to-point links. •Mesh - provides high availability but requires every end system to be connected to every other end system. LAN Topologies: -End devices on LANs are typically interconnected using a star or extended star topology. Star and extended star topologies are easy to install, very scalable and easy to troubleshoot. Early Ethernet and Legacy Token Ring technologies provide two additional topologies: •Bus - All end systems chained together and terminated on each end. •Ring - Each end system is connected to its respective neighbors to form a ring.
Which IOS mode are you in if the Switch> prompt is displayed?
User EXEC Mode
A router with a valid operating system contains a configuration file stored in NVRAM. The configuration file has an enable secret password but no console password. When the router boots up, which mode will display?
User EXEC mode
What is the default SVI on a Cisco switch?
VLAN 1
An employee wants to access the network of the organization remotely, in the safest possible way. What network feature would allow an employee to gain secure remote access to a company network?
VPN
Which feature is a good conferencing tool to use with others who are located elsewhere in your city, or even in another country?
Video Communications
Which option creates a secure connection for remote workers?
Virtual Private Network (VPN)
Which network infrastructure provides access to other networks over a large geographical area, which is often owned and managed by a telecommunications service provider?
WAN
Which option describes a network attack that occurs on the first day that a vulnerability becomes known?
Zero-Day or Zero-Hour
Which feature uses the same cellular technology as a smart phone?
Wireless Broadband
How does an Ethernet switch use the destination MAC addresses of incoming Ethernet frames? Describe what happens if the destination MAC address is in its forwarding table (MAC address table) or is not already in the table. Also, what does a switch do with broadcast frames? [29,7]
[][][] If the destination MAC address is a unicast address, the switch will look for a match between the destination MAC address of the frame and an entry in its MAC address table. If the destination MAC address is in the table, it will forward the frame out the specified port. If the destination MAC address is not in the table, the switch will forward the frame out all ports except the incoming port. This is called an unknown unicast. [][][] If the source MAC address does exist in the table but on a different port, the switch treats this as a new entry. The entry is replaced using the same MAC address but with the more current port number. [][][] If the destination MAC address is a broadcast or a multicast, the frame is also flooded out all ports except the incoming port.
What is the purpose of an Ethernet switch's forwarding table (MAC address table)? How does a switch build its MAC address table? [28,7]
[][][] Switch uses these addresses to forward (or discard) frames to other devices on a network. If a switch just forwarded every frame it received out all ports, your network would be so congested that it would probably come to a complete halt. The switch makes its forwarding decisions based solely on the Layer 2 Ethernet MAC addresses. -An Ethernet switch examines its MAC address table to make a forwarding decision for each frame, unlike legacy Ethernet hubs that repeat bits out all ports except the incoming port. [][][] The switch dynamically builds the MAC address table by examining the source MAC address of the frames received on a port. The switch forwards frames by searching for a match between the destination MAC address in the frame and an entry in the MAC address table.
Which command enables password authentication for user EXEC mode access on a switch?
login
Which is the command to configure a banner to be displayed when connecting to a switch?
banner motd $ Keep out $
What is the structure of an IPv4 address called?
dotted-decimal format
How is the privileged EXEC mode access secured on a switch?
enable secret class
How is an IPv4 address represented?
four decimal numbers between 0 and 255 separated by periods
What is the command to assign the name "Sw-Floor-2" to a switch?
hostname Sw-Floor-2
Which type of access is secured on a Cisco router or switch with the enable secret command?
privileged EXEC
Which command encrypts all plaintext passwords access on a switch?
service password-encrytion
Discuss and differentiate between the following three modes of operation: user EXEC mode, privileged EXEC mode, and global configuration mode. What do the prompts look like for each mode of operation? What commands are used to navigate between the different modes? [9,2]
user EXEC mode -Mode allows access to only a limited number of basic monitoring commands.-It is often referred to as "view-only" mode.It is identified by the CLI prompt that ends with the > symbol. privileged EXEC mode -Mode allows access to all commands and features.-The user can use any monitoring commands and execute configuration and management commands.It can be identified by the prompt ending with the # symbol. global configuration mode -Line Configuration Mode - Used to configure console, SSH, Telnet, or AUX access. -Interface Configuration Mode - Used to configure a switch port or router network interface.
