Chapter 2 - The OSI Model and Networking Protocols

What's the difference between authentication and encryption?

Authentication protocols ensure that the message is from a valid source, whereas encryption protocols ensure that data cannot be read by unintended sources.

What is a PTR record in DNS?

A pointer to the canonical name, which is used to perform a reverse DNS lookup, in which case the name is returned when the query originates with an IP address.

What does arp -s do?

Arp -s manually adds a permanent entry to the ARP cache.

Which of the following ports are associated with H.323? A. 443 B. 1720 C. 5004 D. 3389

B. 1720

Which DNS record is most commonly used to map hostnames to an IP address for a host with IPv6? A. A B. AAAA C. MX D. PTR

B. AAAA

What are SNMP databases called? A. HOSTS B. MIBs C. WINS D. Agent

B. MIBs

Which of the following OSI layers is responsible for establishing connections between two devices? A. Network B. Transport C. Session D. Data link

B. Transport

If files are not text, what transfer mode must FTP be changed to?

Binary

What PDU is for Layer 1?

Bits

Which DNS record stores additional hostnames, or aliases, for hosts in the domain? A. ALSO B. ALIAS C. CNAME D. PTR

C. CNAME

What is a function of ARP? A. It resolves MAC addresses to IP addresses. B. It resolves NetBIOS names to IP addresses. C. It resolves IP addresses to MAC addresses. D. It resolves hostnames to IP addresses.

C. It resolves IP addresses to MAC addresses.

Another feature of SNMP that enables manageability is called what what?

Communities

What is the four letter acronym for the DHCP process?

DORA

What is the H.323 protocol used for?

H.323 is used for call signaling.

How many fields are in a TCP packet?

14 fields

What protocol is the secure alternative to FTP?

SFTP

Does FTP use UDP or TCP?

TCP

True or False? FTP can authenticate end-users?

True

What is the primary benefits of UDP over TCP?

UDP is a connectionless protocol, and as such, requires far less overhead than TCP as a connection-oriented protocol. This makes it extremely popular for in applications such as streaming audio and video, where a small number of dropped packets might not represent a significant problem.

What is the primary command line tool of ICMP that everyone uses?

ping

What is the primary downside of HTTP?

It sends requests in clear text, which is insecure.

What is the primary concern with Telnet?

It's not secure, which is why most administrators use SSH for security purposes.

What is a primary issue with DNS, that DDNS solves?

One of the problems with DNS is that even though its an automatic process, entries and changes to those entries must still be manually performed. Therefore, Dynamic DNS alleviates this issue by enabling hosts to be dynamically registered with the DNS server. By making changes in real time to hostnames, address, and so on, there is less likelihood of not finding a server or site that has been recently added or changed.

What PDU is for Layer 3?

Packets

Which layer of the OSI model converts data from the application layer into a format that can be sent over the network?

Presentation layer - The presentation layer converts data from the application layer into a format that can be sent over the network. It also converts data from the session layer into a format the application layer can understand.

What is the difference between FTP and TFTP?

TFTP is the lightweight version of FTP. It does not have security mechanisms, nor the robust functionality either.

What's the primary purpose of TFTP?

TFTP, being the lightweight version of FTP, is most often associated with simple downloads, such as those associated with transferring firmware to a device such as a router or booting diskless workstations.

What protocol is the successor to SSL?

TLS

What protocol is used for authentication between client and server systems?

TLS handshake protocol

What is TLS used for?

TLS is a security protocol designed to ensure privacy between client/server applications.

The SSH protocol is a more secure alternative to what protocol?

Telnet

What is the purpose of Telnet?

Telnet is used to connect to remote hosts on the network to perform commands for certain tasks.

What is the syntax used within URL requests?

The type of request is (http://), the name of the server contacted would be (www.microsoft.com) for example, and the page requested would be (/support).

What is the well-known port range for TCP/IP?

0 - 1023

What port does SNMP use?

161

If an organization wants to create a MIB, it can apply to the ISO. The ISO then assigns the organization an ID under which it can create MIBs as it sees fit. The assignment of numbers is structured within a conceptual model called what?

A hierarchical name tree.

TCP operates at what layer of the OSI model?

Layer 4

What is an A record in DNS?

An A record in DNS is what maps a hostname to an IP address.

What is an MX record in DNS?

An MX record is used to map entries that correspond to mail exchange systems.

What does arp -a do?

Arp -a displays the entries in the ARP cache.

How does FTP authentication work?

FTP has the mechanism in place to authenticate users. However, rather than create a user account for every user, you can configure FTP server software to accept anonymous logons. When you do this, the username is anonymous, and the password normally is the user's email address. Most FTP servers that offer files to the general public operate in this way.

True or False? DHCP doesn't provide DNS suffixes to clients.

False

True or False? Binary mode is the default transfer mode.

False. ASCII mode is the default transfer mode.

What PDU is for Layer 2?

Frames

What does ICMP do?

ICMP provides error checking and has reporting functionality.

What is the purpose of IGMP?

IGMP is a protocol within the TCP/IP suite that manages multicast groups.

What happens if a DNS servers namespace is too large?

If the DNS namespace is too large, that means the DNS server cannot hold all records for the entire namespace. As a result, the DNS server may not resolve the request for a certain entry. In this case, the DNS server ask another DNS server if it has an entry for the host.

To ensure that SNMP systems offer cross-platform compatibility, MIB creation is controlled by what organization?

International Organization for Standardization (ISO).

What layer of the OSI model does FTP operate at?

Layer 7

What is a NS record in DNS?

NS records are used to store information that identify the name servers in the domain that store information for that domain.

What is NTP?

NTP deals with time synchronization of networks.

What are PTR records for?

PTR records are used for reverse lookups.

What is the difference between port 67 and port 68 for DHCP?

Port 67 is used for the server, whereas Port 68 is used for clients.

What are some pros and cons to connection-oriented TCP communication?

Pros: In a connection-oriented communication, data delivery is guaranteed. The sending device re-sends any packet that the destination does not receive. Communication between the sending and receiving devices continues until the transmission has been verified. Cons: Because of this, connection-oriented protocols have a higher overhead and place greater demands on bandwidth.

What's the difference between public and private SNMP communities?

Public communities are intended for read-only use, whereas private communities are intended for read-write use.

What is the opposite of DNS?

RDNS

What are SNMP communities?

SNMP communities are logical groupings of systems. When a system is configured as part of a community, it communicates only with other devices that have the same community name. In addition, it accepts Get, Get Next, or Set commands only from an SNMP manager with a community name it recognizes.

What protocol, in the TCP/IP suite, facilitates network management functionality?

SNMP is a protocol that facilitates network management functionality.

What does the put command do for FTP?

The put command uploads a single file to the remote host.

SIP also includes a suite of security services. What are several of them?

1. DOS prevention 2. Authentication 3. Integrity protection 4. Encryption

What are the two parts of RTP?

1. Data 2. Control

What would be a few examples of a top-level domain for DNS?

1. .com 2. .edu 3. .de

What ports do the HTTPS, RDP, and MGCP protocols use?

1. 143 2. 3389 3. 2427 and 2727

What two ports does FTP use?

1. 20 2. 21

What two ports does MGCP use?

1. 2427 2. 2727

What two ports does RTP use?

1. 5004 2. 5005

What two ports does SIP use?

1. 5060 2. 5061

What does "destination unreachable" and "Time exceeded" for ICMP?

1. Destination unreachable means the destination cannot be contacted. 2. Time exceeded means the time to live (TTL) packet of a datagram has been exceeded.

What are several features that TCP provides?

1. Flow control 2. Sequencing 3. Error detection 4. Error correction

Besides best-effort delivery, what two things does IP provide?

1. Fragmentation, and reassembly of network transmissions 2. IP addressing

How does ARP work in simple terms?

1. Host A pings Host B. 2. IP determines if Host B resides on the same network as Host A. 3. If Host B is on the same network, it consults the ARP cache on the local device to see whether it already has an entry for Host A. 4. If Host A does not have Host B within its ARP cache, a broadcast is sent out to confirm the identify of Host B. 5. The broadcast is then used to ask all devices within the same subnet to send back its MAC address if the requested IP address matches. 6. If Host B does not reside on the same network, Host A will reach out to the default gateway, and ARP will traverse the network until it gets to its intended destination.

What would be a few examples of a second-level domain for DNS?

1. Microsoft 2. Redhat 3. Acme

What are the two communities are used by default in SNMP?

1. Public community. 2. Private community.

What are two common multicasting groups?

1. Routers 2. Teleconferencing clients

What two protocols does VoIP use?

1. SIP 2. RTP

Which of the following are considered transport protocols? (Choose the two best answers). A. TCP B. IP C. UDP D. THC

1. TCP C. UDP

How does TCP work?

1. TCP sends a message called a SYN to the target host. 2. The target host opens a connection for the request and sends back an acknowledgement message called a SYN ACK. 3. The host that originated the request sends back another ACK, saying that it has received the SYN ACK message, and that the session is ready to be used to transfer data.

What protocol is used at Layer 6?

1. TLS

What are three common ARP command switches?

1. arp -a 2. arp -s 3. arp -d

What are nine of the most common FTP commands?

1. ls 2. cd 3. lcd 4. put 5. get 6. mput 7. mget 8. binary 9. ascii

Systems that ask DNS servers for a hostname-to-IP address mapping are called what two things?

1. resolvers 2. DNS clients

An example of a FQDN is www.comptia.org. What are each of the individual parts called?

1. www is the host 2. comptia is the second-level domain 3. .org is the top-level domain

What port does H.323 use?

1720

HTTP is defined in what RFC?

2068

What port does SSH use?

22

What is the Class D range for multicasting?

224.0.0.0 - 239.255.255.255

What port does Telnet use?

23

What port does SMTP use?

25

What port does RDP use?

3389

How many fields are in a UDP packet?

4 fields

What port does SMB use?

445

What is the total number of ports available to TCP/IP?

65,535

What port does TFTP use?

69

What port does HTTP use?

80

SMTP is defined in what RFC?

821

What is a CNAME record in DNS?

A CNAME record is used to create alias records for a system.

What is a CNAME record in DNS?

A CNAME stores additional hostnames, or aliases, for hosts in the domain. A CNAME record specifies an alias or nickname for a canonical hostname record in a DNS database. CNAME records give a single computer multiple names (aliases).

What is a MX record in DNS?

A MX record stores information about where mail for the domain should be delivered.

What is a SOA record in DNS?

A State of Authority (SOA) record contains information on DNS zones and other DNS records. A DNS zone is the part of a domain for which an individual DNS server is responsible. Each zone contains a single SOA record.

What is a basic explanation of how DNS works?

A client asks to reach the first server at mycoltd.com; the router turns to the DNS server for an IP address associated with that server; and after the address is returned, the client can establish a connection.

How does the DNS resolution process work?

A client device asks the DNS server to resolve server1.mycoltd.com. The DNS server then checks its namespace, and if full, goes to its default gateway, or router. The router will then forward this request to server1.mycoltd.com. Afterward, server1.mycoltd.com will provide its IP address of 192.168.3.43.

What is the most common DNS record?

A record

If an SNMP agent recognizes that a certain configured threshold has passed, it will let the SNMP manager know. How does it do this?

A trap on the SNMP agent will be sent to the NMS. The NMS will then perform an action depending on the configuration. Basic NMS systems might sound an alarm or flash a message on the screen. Other, more advanced products might send a paper message, dial a cell phone, or send an email.

What are two features supported in SNMPv3 and not previous versions? A. Authentication B. Dynamic mapping C. Platform independence D. Encryption

A. Authentication D. Encryption

What are the logical groups of SNMP systems known as? A. Communities B. Pairs C. Mirrors D. Nodes

A. Communities

TCP is an example of what kind of transport protocol? A. Connection oriented B. Connection reliant C. Connection dependent D. Connectionless

A. Connection oriented

What is a AAAA record in DNS?

AAAA records stores information for IPv6 addresses. It is most commonly used to map hostnames to an IPv6 address for a host.

What is ARP cache?

ARP cache is a table of Layer 3 to Layer 2 mappings, and whether or not it was learned dynamically, or statically.

What is the purpose of ARP?

ARP resolves Layer 3 to Layer 2 addresses. In layman terms, IP to MAC.

What does arp -d do?

Arp -d deletes an entry from the ARP cache.

By default, which protocols uses port 68? A. DHCP B. DNS C. SMB D. SMTP

B. DHCP

During a discussion with your ISP's technical support representative, he mentions that you might have been using the wrong FQDN. Which TCP/IP-based network service is he referring to? A. DHCP B. WINS C. SNMP D. DNS

D. DNS

What is the function of NTP? A. It provides a mechanism for sharing of authentication information. B. It is used to access shared folders on a Linux system. C. It is used to communicate utilization information to a central manager. D. It is used to communicate time synchronization information between systems.

D. It is used to communicate time synchronization information between systems.

Which of the following protocols offers guaranteed delivery? A. FTP B. IPX C. IP D. TCP

D. TCP

The lease duration in the DHCP process is a part of what DHCP packet?

DHCPOffer

True or False? Applications that use RTP are more sensitive to packet loss?

False. Applications are more sensitive to delays, rather than packet loss.

True or False? RDP sends data over its connection.

False. RDP is only used for performing keystrokes, taking screenshots, etc.

True or False? SNMP is a network management system (NMS)?

False. SNMP is not an NMS. Rather, it's simply the protocol that makes NMS possible.

True or False? TFTP offers directory navigation.

False. TFTP offers no such capabilities, and as such, TFTP requires that you request no only exact what you want but also the particular location.

True or False? SSH on your client can be a different version than SSH on your server?

False. They have to be the same SSH version, whether that be SSHv1 or SSHv2.

What is network fragmentation?

Fragmentation is necessary because the MTU size is limited in IP. In other words, network transmissions that are too big to traverse the network in a single packet must be broken into smaller chunks and reassembled at the other end.

The domain name, along with any subdomains is called what?

Fully Qualified Domain Name (FQDN)

HTTP uses what technology to determine what page should be downloaded from the remote server.

HTTP uses URLs to determiner what page should be downloaded and viewed locally.

What protocol introduces security to HTTP?

HTTPS (also known as HTTP over SSL)

What is IP?

IP is a protocol used to transport data from one node on a network to another. IP is connectionless, which means that it doesn't guarantee the delivery of data; it simply makes its best effort to do so. To ensure that transmissions sent via IP are completed, a higher-level protocol such as TCP is required.

What is the purpose of LDAP?

LDAP is a protocol that provides a mechanism to access and query directory service systems. In context of the exam, these systems are most likely to be UNIX based or Microsoft AD based.

What layer of the OSI model does a hub operate?

Layer 1

What layer of the OSI model does IP operate at?

Layer 3

What layer of the OSI model does NNTP operate at?

Layer 7

What is an alternative to RTCP?

MGCP

What is the purpose of multicasting?

Multicasting is used for when you want to target a particular group of computers to receive specific content.

What is NNTP?

NNTP is the Network News Transfer Protocol.

What is the purpose of RARP?

RARP maps MAC addresses to IP addresses.

What is the RDP equivalent for servers?

RDP is used for client systems, but Remote Desktop Services (RDS) provides a way for client systems to connect to a server.

TFPT is defined in what RFC?

RFC 1350

What RFC defines IMAP4?

RFC 1731

What RFC defines POP3?

RFC 1939

What RFC is DHCP defined in?

RFC 2131

UDP is defined in what RFC?

RFC 768

IP is defined in what RFC?

RFC 791

ICMP is defined in what RFC?

RFC 792

TCP is defined in what RFC?

RFC 793

ARP is defined in what RFC?

RFC 826

Telnet is defined in which RFC?

RFC 854

What RFC is RARP defined in?

RFC 903

What RFC is NTP defined in?

RFC 958

FTP is defined in what RFC?

RFC 959

What RFC is NNTP defined in?

RFC 977

What protocol does the control portion of RTP use?

RTCP

What is Reverse DNS?

Rather than resolving hostnames to IP address with conventional DNS, reverse lookups will instead resolve IP addresses to hostnames.

How is reverse lookups performed?

Reverse lookups are accomplished by using pointer (PTR) records.

What is the primary benefit of SFTP?

SFTP utilizes SSH, providing not only authentication between end-points, but also encryption.

What is different between SMTP and POP3 or IMAP4?

SMTP can send, and receive mail whereas POP3 and IMAP4 can only receive mail.

On each device to be managed and monitored via SNMP, the software is called what?

SNMP agent

SNMP agents can communicate the occurrence of certain events to the SNMP manager as they happen. These messages are known as what?

SNMP traps

What is the purpose of Management Information Bases (MIB)?

SNMP uses databases of information called MIBs to define what parameters are accessible, which of the parameters are read-only, and which can be set. MIBs are available for thousands of devices and services, covering every imaginable need and must be configured with the exact same information.

What are the different SNMP commands?

SNMP uses the Get and Get Next commands to read information, whereas the Set command is used by SNMP managers to make remote changes. In addition, if you have a large sequence of Get Next commands to perform, you can use the Walk command to automatically move through them.

What's the primary difference between SNMPv1 or v2, and SNMPv3?

SNMPv3 supports authentication and encryption.

What is the core difference between POP3 and IMAP4?

Security. The password to access a mailbox for POP3 is transmitted over the network in clear text. Which means, if someone wanted to they could use a sniffer, and determine the password no time flat. This is where IMAP4 comes into play. IMPA4's authentication system is more sophisticated.

What PDU is for Layer 4?

Segments

What is the purpose of SMB?

Server Message Block (SMB) is used on a network for providing access to resources such as files, printers, ports, and so on that are running on Windows.

ICMP also performs source quenching. What is this?

Source quenching is used when the receiving host cannot handle the influx of data at the same rate as the data is sent. To slow down the sending host, the receiving host sends ICMP source quench messages, telling the sender to slow down. This actions prevents packets from dropping and having to be re-sent.

What Layer 4 protocol does NNTP use?

TCP

What Layer 4 protocol does SMTP use?

TCP

How is TCP connection-oriented?

TCP is connection-oriented because it accommodates lost or dropped packets by asking the sending device to retransmit them. They can do this because they wait for all the packets in a message to be received before considering the transmission complete. On the sending end, connection-oriented protocols also assume that a lack of acknowledgement is sufficient reason to retransmit.

What is the purpose of SIP/RTP?

The Session Initiation Protocol (SIP) or Real-time Transport Protocol are used for Voice over IP (VoIP).

What does the ASCII command do for FTP?

The ascii command switches the transfer mode into ASCII mode.

What does the binary command do for FTP?

The binary command switches the transfer mode into binary mode.

What does the cd command do for FTP?

The cd command changes the working directory on the remote host.

In an SNMP configuration, the central system is known as what?

The central system is called a manager.

What does the control part of RTP do?

The control portion supports real-time conferencing of groups of any size within the Internet.

What does the get command do for FTP?

The get command downloads a single file from the remote host.

What does the lcd command do for FTP?

The lcd command changes the working directory on the local host.

What does the ls command do for FTP?

The ls command lists files in the current directory on the remote system.

What does the mget command do for FTP?

The mget command downloads multiple files from the remote host.

What does the mput command do for FTP?

The mput command uploads multiple files to the remote host.

What FTP command uploads multiple files to the remote host?

The mput command.

What is the purpose of using ping?

The ping utility is used to send a stream of ICMP echo requests to a remote host. If the host is on the network, and can respond, it does so by sending echo reply messages back to the sending host.

What is the purpose of the Walk command?

The purpose of the Walk command is to save a SNMP manager's time: you issue one command on the root node of a sub-tree and the command "walks" through, getting the value of every node in the sub-tree.

Some people call SNMP managers or NMSs trap managers. Why is this misleading?

The reason why calling SNMP managers or NMSs trap managers misleading is because they can do more than just accept trap messages from agents.

Although the SNMP manager resides on a PC, each device that is part of the SNMP structure also needs to have SNMP functionality enabled. What is the software component that performs this called?

The software component that enables SNMP functionality is called an agent.

With TCP, a data session is established through a three-step process. This is known as what?

Three-way handshake

True or False? DHCP settings push domain suffix search lists to DNS clients. When such a list is specifically given to a client, the client uses only that list for name resolution.

True

True or False? HOST files resolution is still supported by most platforms?

True

True or False? SIP uses both TCP and UDP?

True

How is UDP connectionless?

UDP is connectionless because it offers only a best-effort delivery mechanism. Basically, the information is just sent; there is no confirmation that the data has been received. If an error occurs in the transmissions, there is no mechanism to resend the data, so transmissions made with connectionless protocols are not guaranteed.

Does TFTP use UDP or TCP?

UDP. Since TFTP is the lightweight version of FTP, it only makes sense that it uses the lightweight version of TCP for transferring minor files.

What is the name of the packet on a system configured to use DHCP broadcasts when it comes onto the network?

When a system configured to use DHCP comes onto the network, it broadcasts a special packet that looks for a DHCP server. This packet is known as the DHCPDISCOVER packet.

What is the difference between buffering, and windowing?

1. Buffering - This methods temporarily stores data, and waits for the destination device to become available. Buffering can cause a problem if the sending device transmits data much faster than the receiving device can manage. 2. Windowing - This method sends groups of segments that require only one acknowledgement. The size of the window (that is, how many segments fit into one acknowledgement) is defined when the session between the two devices is established. As you can imagine, the need to have only one acknowledgement for every, say, five segments can greatly reduce overhead.

Layer 4 has three important, yet distinct mechanisms for transporting data. What are they?

1. Error checking: Protocols at the transport layer ensuring that data is correctly sent or received. 2. Service addressing: A number of protocols support many network services. The transport layer ensures that data is passed to the right service at the upper layers of the OSI model. 3. Segmentation: To traverse the network, blocks of data need to be broken into packets of a manageable size for the lower layers to handle. This process, called segmentation, is the responsibility of the transport layer.

What are three important, yet distinct data formats used by Layer 6?

1. Graphic files: JPEG, PNG, and GIF are graphic file formats that require the data to be formatted in a certain way. 2. Text and data: Layer 6 can translate data into different formats, such as ASCII and EBCDIC. 3. Sound/video: MPEG, MP3, and MIDI files all have their own data formats to and from which data must be converted.

What are the two sub-layers of Layer 2?

1. MAC layer - The MAC layer references back to MAC addresses, and how they are physically burned into each devices NIC. This also controls access to network media, and is further defined in the IEEE 802.1 standard. 2. LLC layer - The LLC layer is responsible for the error and flow-control mechanisms of the data link layer. The LLC layer is specified in the IEEE 802.2 standard.

What port is name service?

116

What port is NetBIOS name server?

137

What port is NetBIOS datagram server?

138

What is the difference between DHCP reservations and exclusions?

A reservation is used to reserve a range of IP addresses for network hosts. Exclusions on the other hand are used when you want a certain range of addresses not given out to a set of devices.

At what layer of the OSI model do FTP and TFTP map?

Application layer - FTP and TFTP map to the application layer.

What type of network traffic is used for DHCP acknowledgements?

Broadcasts

When a client device accepts a DHCPOffer packet from a DHCP server, it will notify said server via what DHCP packet?

DHCPRequest

What are some of the most basic services that the application layer provides?

File sharing and printing.

What is a primary con of HOST files regarding IP addresses, aliases, etc?

HOST files were prone to human error, and became increasingly cumbersome as the Internet grew. Therefore, an automatic method was required, and as such DNS was born.

What IEEE standard is for the LLC sub-layer of Layer 2?

IEEE 802.2

Can DHCP relays or IP helpers do more?

IP helper

What layer of the OSI model does a NIC operate?

Layer 2

What layer of the OSI model does a switch operate?

Layer 2

What layer of the OSI model does a wireless bridge operate?

Layer 2

What is the purpose of an IP helper?

The IP helper is what's used to forward broadcasts for DHCP/BOOTP, TFTP, DNS, TACACS, time service, and NetBIOS.

What is the OSI model?

The OSI model is a conceptual idea created by the ISO to describe how networking, applications, and what have you work, and relate in a real-world setting.

What is the difference between the TCP/IP and OSI model?

The TCP/IP model is real-world architecture that describes networking, similarly to the OSI model. However, while the OSI model is only theoretical, it's used far more frequently than the TCP/IP model when describing how network communications operates. This can range from the physical electrical bits that transfer over an Ethernet cable, to how IP routes across numerous routers to get to its intended destination.

What are the characteristics of Layer 7?

The application layer is what receives requests and data from end-users, and passes them to the lower layers of the OSI model to be processed.

What are the characteristics of Layer 2?

The data link layer is responsible for transferring data to the physical layer so it can transmit over the network. It's also responsible for error detection, error correction, and hardware addressing.

Within DNS, what is the domain name, along with any subdomains, called?

The domain name, along with any subdomains, is called the full qualified domain name (FQDN) because it includes all the components from the top of the DNS namespace to the host.

What is a frame at Layer 2?

The frame is a grouping of data at Layer 2.

What are the characteristics of Layer 3?

The network layer is responsible for routing, which dictates how traffic is forwarded from one network to another. It's also responsible for route selection, also known as best path selection. This determines which route is optimal for the available traffic.

What is a packet at Layer 3?

The packet is a grouping of data at Layer 3.

What are the characteristics of Layer 1?

The physical layers hardware determines the type of cable, connector type, pinout format, etc. The topology refers to how the network is physically laid out. Common topologies include ring, mesh, star, bus, and hybrid. Different protocols and technologies such as USB, Ethernet, DSL, ISDN, T-carrier links (T1 and T3), and SONET operate at this layer. And lastly, the physical layer defines what voltage is used, the frequency at which the signal carries data. Also, these characteristics dictate the speed, bandwidth, and maximum distance over a specific cable type.

What is another, if not the most important aspect of Layer 6?

The presentation layer is also responsible for encryption. This makes sense, as Layer 6 is in essence the data-format translator. And since encryption deals with scrambling data to make it illegible, it is an obvious place for encryption and decryption to take place.

What are the characteristics of Layer 6?

The presentation layer's basic function is to convert the data intended for or received from the application layer into another format. Such conversion is necessary because of how data is formatted so that it can be transported across the network.

What file is used for Linux when specifying DNS suffix entries?

resolve.conf file

What two ports are used for DHCP?

1. 67 2. 68

What are several different type of protocols that operate at Layer 3?

1. ARP 2. RARP 3. ATM 4. IS-IS 5. IPsec 6. MPLS

Layer 4 is responsible for flow control, which refers to how the receiving device can accept data. What are the two common methods of flow control?

1. Buffering 2. Windowing

What are the two important, yet distinct aspects of Layer 2?

1. Data transfer from Layer 2 to Layer 1. 2. Error detection, error correction, and hardware addressing.

What are the three important, yet distinct mechanisms of Layer 4?

1. Error checking 2. Service addressing 3. Segmentation

What are several different type of protocols that operate at Layer 2?

1. HDLC 2. L2TP 3. PPP 4. PPTP 5. STP 6. VLAN

What are the four important, yet distinct aspects of Layer 1?

1. Hardware type 2. Physical topology 3. Different protocols and technologies 4. Voltage, frequency, speed, bandwidth, and distance

What are several protocols that operate at Layer 5?

1. NetBIOS 2. NFS 3. SMB

What are the four layers of the TCP/IP model?

1. Network or Link 2. Internet 3. Transport 4. Application

What are three primary benefits of DHCP?

1. No administrator overhead over the long term. 2. Duplicate addresses via human error is eliminated. 3. No need to reconfigure addresses when the subnet size is changed.

What is the order of layers from bottom-up regarding the OSI model?

1. Physical 2. Data Link 3. Network 4. Transport 5. Session 6. Presentation 7. Application

What are the two important, yet distinct aspects of Layer 3?

1. Routing 2. Route selection

What are several protocols used at Layer 7?

1. SSH 2. BGP 3. DHCP 4. DNS 5. NTP 6. RTP 7. SIP 8. SMTP 9. SMB 10. FTP 11. HTTP 12. HTTPS 13. IMAP 14. POP3

What are two ways that routes can be configured?

1. Statically 2. Dynamically

There are two methods of assigning IP addresses to host machines. What are they?

1. Statically via manual configuration 2. Dynamically via DHCP

What are the two protocols that operate at Layer 4?

1. TCP 2. UDP

What port is time service?

37

What port is TACACS?

49

When a network host is assigned a DHCP address, it will attempt to renew its lease at two various points. What are they?

50% and 85%

What port does DNS use?

53

What port is DNS?

53

What port is used for a DHCP/BOOTP server?

67

What port is used for a DHCP/BOOTP client?

68

What port is TFTP?

69

What is the purpose of a DHCP relay?

A DHCP relay is an agent on a router that acts as a go-between for clients and the DHCP server. This is necessary for clients who reside on different subnets, as they cannot communicate on the network until the server assigns it the appropriate information.

A comment in a HOSTS file is preceded by what?

A hash symbol (#)

What is the difference between a static route, and a dynamically learned route?

A static route is a route that was manually added to the routing table. A dynamic route is learned via a routing protocol, such as RIP, OSPF, EIGRP, etc.

Which of the following are sublayers of the data link layer? A. MAC B. LCL C. Session D. LLC

A. MAC D. LLC

Which of the following is not a common packet sent during the normal DHCP process? A. DHCPACK B. DHCPPROVE C. DHCPDISCOVER D. DHCPOFFER

B. DHCPPROVE

At which two OSI layers can a switch operate? (Choose two.) A. Layer 1 B. Layer 2 C. Layer 3 D. Layer 4

B. Layer 2 C. Layer 3

One of the programmers has asked that DHCP always issue his workstation the same IP address. What feature of DHCP enables you to accomplish this? A. Stipulation B. Rider C. Reservation D. Provision

C. Reservation

If you want to supply a host with a specific IP address from DHCP, what would you configure?

DHCP has an option called reservations where you can assign computers specific IP addresses.

What is a primary con to DHCP?

DHCP is dynamic, also known as automatic. Therefore, in order to operate, it has to use broadcasts to verify devices are on the network. This generates network traffic, albeit negligible depending on size.

When the DHCP server finalizes the offer, what DHCP packet is used to complete the DHCP process?

DHCPACK

When a network device comes online, and looks for a DHCP server, what DHCP packet is used?

DHCPDiscover

What is the purpose of DNS?

DNS is responsible for resolving hostnames to IP addresses. A good example would be opening the Command Prompt, typing nslookup www.google.com, and having it return with its IP address of 142.250.217.100.

What does DORA stand for in regards to DHCP?

Discover Offer Request Acknowledge

What is dynamic DNS?

Dynamic DNS is a newer system that enables host to be dynamically registered with the DNS server.

What IEEE standard is for the MAC sub-layer of Layer 2?

IEEE 802.1

What is the primary benefits of DNS?

It helps create an easy to remember system for humans. IP addresses are difficult to memorize, whereas www.facebook.com is a common website that everyone knows.

What layer of the OSI model does an access point operate?

Layer 2

What layer of the OSI model does a router operate?

Layer 3

What is the primary difference between Layer 4 and Layer 5 in regards to the management of data between two nodes?

Layer 4 is responsible for setting up, and maintaining the connection between two nodes, whereas Layer 5 performs the same function but on behalf of the application itself.

What is a common misconception about the application layer?

People think the application layer presents applications used on a system, such as your web browser, word processor, spreadsheet, etc. Rather, it defines the processes or protocols that enable applications to use network services.

What are some pros and cons of static IP addresses?

Pros: A network host will always use its manually assigned IP address. This consistency helps when troubleshooting. Cons: It's difficult to manage an increase number of devices when using static IP addresses. The administrative overhead is too large to manage past a certain point.

Pop Quiz: DHCP is protocol-dependent, or platform-dependent?

Protocol-dependent

Why are routing protocols used?

Routing protocols in essence create convenience., Static routes on the other hand, especially in large numbers require a lot of administrative overhead, which is time consuming. So, routing protocols help alleviate those concerns while also communicating routing information between different network devices.

What is the purpose of DNS suffixes?

Suffixes define the DNS servers to be used and the order in which to use them. DHCP settings can push a domain suffix search list to DNS clients. When such a list is specifically given to a client, the client uses only that list for name resolution.

What is the primary difference between TCP and UDP?

TCP is connection oriented, whereas UDP is connectionless. Meaning, TCP ensures segments of data correctly gets delivered to its destination, albeit more slowly whereas UDP is fast, but if data gets dropped, it doesn't care.

What are the characteristics of Layer 5?

The session layer is responsible for managing and controlling the synchronization of data between applications on two devices. It does this by establishing, maintaining, and breaking sessions.

What are the characteristics of Layer 4?

The transport layer is responsible for transporting data between network devices.

When DHCP assigns an IP address to a host machine for a pre-determined amount of time, what is that key term called?

This is referred to as the lease time.

True or False: Transport protocols, such as UDP, map to the transport layer of the OSI model and are responsible for transporting data across the network.

True. Transport protocols map to the transport layer of the OSI model and are responsible for transporting data cross the network. UDP is a transport protocol, including TCP.

What is the name used for ranges of IP addresses available within DHCP?

Within DHCP, ranges of IP addresses are known as a DHCP scope.