Networking MIDTERM
You are setting up a DNS zone and have been asked to create SPF and DKIM records. What type of DNS record will hold this information?
TXT record
There are several interior gateway protocols, but only one current exterior gateway protocol. What is this protocol, and what characteristics does it have
The Border Gateway Protocol (BGP) is the only current exterior gateway protocol, and has been dubbed the "protocol of the Internet." Whereas OSPF and IS-IS scouting parties only scout out their home territory, a BGP scouting party can go cross-country. BGP spans multiple autonomous systems and is used by edge and exterior routers on the Internet. Here are some special characteristics of BGP: * path-vector routing protocol-Communicates via BGP-specific messages that travel between routers over TCP sessions. * efficient-Determines best paths based on many different factors. * customizable-Can be configured to follow policies that might, for example, avoid a certain router, or instruct a group of routers to prefer one particular route over other available routes
You are troubleshooting a DNS issue on a Linux system, and need to test the resolution of your domain mycompany.com MX record using Google's DNS server with the IP address of 8.8.8.8. What dig command will accomplish this?
dig @8.8.8.8 mycompany.com MX
In IPv6, what field is used to indicate what sequence of packets from one source to one or multiple destinations a packet belongs to?
flow label
What IPv6 field is similar to the TTL field in IPv4 packets?
hop limit
On a Linux-based system, what command can be used to display TCP/IP information associated with every interface on the system?
ifconfig -a
At the Transport layer of the OSI, what is used to find and communicate with a particular application running on a host?
port numbers
You have been tasked with the replacement of OSPF with EIGRP throughout your organization, which consists of a mixture of Cisco routers and routers from other vendors. What statement is accurate?
EIGRP may not be available on non-Cisco routers.
If a host's IPv6 address contains the network adapter's MAC address within the last 64 bits of the IPv6 address, what standard is being used?
EUI-64
UDP provides error checking, but not sequencing.
False
Z-Wave transmissions have a range of up to 50m per hop, and can tolerate up to 8 hops through repeaters.
False
What scenario describes an evil twin attack?
A malicious access point is configured with the SSID of a non-malicious public access point.
Why should you terminate coaxial cable with connectors that are rated for the exact cable type?
A mismatched connector will have different impedance ratings, causing data errors.
When troubleshooting wireless issues, what statement is accurate?
Access points that use overlapping channels can cause interference with each other if they are too close.
A Windows computer on your network is having issues resolving queries for a specific domain, but not other domains. Other computers on the same network resolve the name just fine. What command can you issue that might fix the problem?
ipconfig /flushdns
In Linux, what command can be used for viewing and setting wireless interface parameters?
iwconfig
Routing protocols that enable routers to communicate beyond neighboring routers, allowing each router to independently map the network, are known as which type of protocols?
link-state protocols
You've been handed a fiber with a 1.25-mm ferrule that requires a connector. What is the most commonly used connector for this ferrule size?
local connector
What 802.11 frame type is involved in association and reassociation, including probe and beacon frames?
management frames
What kind of tool can you use to measure voltage on a cable length?
multimeter
The use of multiple antennas on an access point to issue a signal to one or more receivers is enabled by what 802.11 innovation?
multiple input-multiple output (MIMO)
With a FQDN of ftp1.dallas.mycompany.com, what part is the domain name?
mycompany.com
A wireless node that is in active scanning mode transmits what special type of frame in order to find available access points?
probe frame
In a TCP segment, what field indicates how many bytes the sender can issue to a receiver before acknowledgment is received?
sliding-window
What type of device can be used to assess the quality of a wireless signal?
spectrum analyzer
The Border Gateway Protocol is considered to be a hybrid routing protocol.
True
The Wi-Fi Protected Setup PIN can be easily cracked through a brute force attack.
True
The Wireless Personal Area Network (WPAN) is defined in the 802.15 standard.
True
The cost of upgrading infrastructure has been a major factor in the slow adoption of IPv6.
True
The most secure Wi-Fi communication is made possible by combining a RADIUS server with WPA or WPA2, known as WPA-Enterprise or WPA2-Enterprise, respectively
True
UDP port 123 is utilized by the Network Time Protocol service.
True
If you need to evaluate Wi-Fi network availability as well as optimize Wi-Fi signal settings and identify security threats, what tool should you use?
Wi-Fi analyzer
The pathping utility sends 10 pings per hop by default.
False
The LLC sublayer is primarily concerned with managing MAC addresses in message frames.
False
Near-field communication devices send data at what fixed frequency?
13.56 MHz
In an 802.11 data frame, what is the maximum amount of data that can be sent?
2312 bytes
802.11ac Wave 2 devices can theoretically support how much maximum throughput?
3.47 Gbps
How many data streams are used in 802.11ac Wave 2 devices?
4 data streams
In an 802.11 data frame, what is the size of the frame check sequence field?
6 bytes
Which of the following statements regarding the 802.11ac standard is NOT accurate?
802.11ac access points function more like a hub than a switch.
The wireless spectrum, as defined by the FCC, spans between which two frequencies?
9 kHz and 300 GHz
Describe the 802.11a standard, and detail some of its history and advantages / disadvantages versus other 802.11 standards.
Although the 802.11a task group began its standards work before the 802.11b group, 802.11a was released after 802.11b. The higher throughput of 802.11a, as compared with 802.11b, is attributable to its use of higher frequencies, its unique method of modulating data, and more available bandwidth. Perhaps most significant is that the 5-GHz band is not as congested as the 2.4-GHz band. Thus, 802.11a signals are less likely to suffer interference from microwave ovens, cordless phones, motors, and other (incompatible) wireless LAN signals. However, higher-frequency signals require more power to transmit, and they travel shorter distances than lower-frequency signals. As a result, 802.11a networks require a greater density of access points between the wired LAN and wireless clients to cover the same distance that 802.11b networks cover. The additional access points, as well as the nature of 802.11a equipment, make this standard more expensive than either 802.11b or 802.11g. For this and other reasons, 802.11a is rarely preferred.
The 802.11 standard specifies the use of what technique in order to minimize the potential for collisions?
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
Which Bluetooth power class allows for a maximum power output of 100 mW and a range of up to 100 m?
Class 1
Why should an access point not always utilize all the power it has for broadcasting wireless signals?
Each access point's power level, or the strength of the signal the access point emits, should be optimized for the geographic area covered by that AP. Power levels that are too low will result in dropped signals as clients roam to the peripheral areas of the AP's range. However, maxed out power levels will result in too much overlap between AP coverage areas, causing clients from other coverage areas to attempt to connect with APs that are farther away but transmitting the stronger signal.
Due to many vulnerabilities and a short key length, the WPA security standard was replaced with WEP.
False
Infrared technology utilizes an LED that emits light with shorter wavelengths than red light.
False
NFC tags are very expensive and cannot be purchased blank, requiring them to be pre-loaded.
False
How does configuration of wireless clients for wireless access in an enterprise environment differ from normal setup?
In an enterprise environment, configuring clients for wireless access to the network can entail a much more involved, two-part process: * on-boarding-Users or network technicians install a specific app, called an agent, on a user's device, whether the device is a smartphone, laptop, or tablet. This gives the device trusted access to certain portions of the network. Access to email services, file-sharing services, and certain network administrative features might all be controlled by the device's permission levels enabled by on-boarding that device. * off-boarding-The reverse procedure involves removing the agent. For security purposes, network administrators need a feature that allows them to do this remotely, in case a device is lost or stolen. This feature, called a remote wipe, clears a device of all important information, permissions, and apps without having physical access to the device. It might even allow you to completely disable the device, making any network or data access impossible.
What is the difference between war driving and war chalking?
In war driving, a hacker searches for unprotected wireless networks by driving around with a laptop or smartphone configured to receive and capture wireless data transmissions. (The term is derived from the term war dialing, which is a similar tactic involving old, dial-up modems.) War driving is surprisingly effective for obtaining private information. War chalking occurs when a hacker discovers vulnerable access points, and makes this information public by drawing symbols with chalk on the sidewalk or wall within range of a wireless network. The symbols, patterned after marks that hobos devised to indicate hospitable places for food or rest, indicate the access point's SSID and whether it's secured. Alternatively, many websites offer maps of these open networks, as reported by war drivers.
How does refraction affect the propagation of a wireless transmission?
It distorts the signal as it travels into and through a different transmission medium
When using RFID, what is an ARPT (Active Reader Passive Tag)?
It is a tag that is activated by an active reader, and uses power from the reader's radio to power its transmission.
What is the purpose of the Layer 2 LLC sublayer?
It is used to handle multiplexing, flow and error control, and reliability.
At what layer of the OSI model do the 802.11 standards vary?
Physical layer
What optional protocol can be used in 802.11 to reserve the medium for one node's use?
RTS/CTS (Request to Send/Clear to Send)
You are troubleshooting a client's wireless networking issue. Which of the following will prevent the client from connecting to the network?
The client has a wireless profile configured for the "campus" SSID, but the access point is broadcasting the "CAMPUS" SSID.
What are some of the different types of wireless topologies that can be created?
Some of the different types of wireless topologies are as follows: * ad hoc-A small number of nodes closely positioned transmit directly to each other without an intervening connectivity device. * infrastructure-An intervening connectivity device, a WAP (wireless access point) or AP (access point), accepts wireless signals from multiple nodes and retransmits them to the rest of the network. To cover its intended range, an access point must have sufficient power and be strategically placed so that all connected nodes can communicate with it. * mesh-Several access points work as peer devices on the same network, where the AP devices cooperate to provide more fault tolerant network access to clients. A wireless controller might be used only initially to configure the APs, or the APs might remain connected to the wireless controller for continued management
What is the hidden node problem, and how can it be mitigated?
The hidden node problem occurs where a node is not visible to other nodes on the other side of a coverage area. One way to ensure that packets are not inhibited by other transmissions is to reserve the medium for one station's use. In 802.11, this can be accomplished through the optional RTS/CTS (Request to Send/Clear to Send) protocol. RTS/CTS enables a source node to issue an RTS signal to an access point requesting the exclusive opportunity to transmit. If the access point agrees by responding with a CTS signal, the access point temporarily suspends communication with all stations in its range and waits for the source node to complete its transmission.
How does the 802.11 data frame indicate how a large packet should be fragmented?
The sequence control field indicates how packets will be subdivided.
Diffraction has what affect on a wireless signal's propagation?
The signal is split into secondary waves that continue in the direction in which they split.
Radiation patterns can be used to classify antennas into what two basic categories?
The two basic categories that antennas can be classified under are: * unidirectional antenna (also called a directional antenna)-Issues wireless signals along a single direction. This type is used when the source needs to communicate with one destination, as in a point-to-point link, or in a specific area. A satellite downlink (for example, the kind used to receive digital TV signals) uses directional antennas
Most wireless devices use one of two technologies to avoid interference. What are these technologies?
The two technologies used are as follows: * FHSS (frequency hopping spread spectrum)-Short bursts of data are transmitted on a particular frequency within the band and the next burst goes to the next frequency in the sequence. Frequency hopping can happen hundreds of times a second. FHSS is cheaper to implement than DSSS and performs better than DSSS in crowded, indoor environments. * DSSS (direct sequence spread spectrum)-Data streams are divided and encoded into small chunks, called chips, which are spread over all available frequencies within one of three, wide channels, all at the same time. The process of dividing and encoding the data is called chipping, and the spreading ratio used to transform the data is called the chipping code, which is unique to each device. DSSS uses the available bandwidth more efficiently than FHSS and tends to have a higher throughput.
All wireless signals are carried through the air by electromagnetic waves.
True
An 802.11 data frame contains four address fields, in contrast to the two address fields in 802.3 Ethernet.
True
Why should the WPS PIN feature be avoided if possible?
WPS (Wi-Fi Protected Setup) is a user-friendly but not very secure-security setting available on some consumer-grade APs. Part of the security involves requiring a PIN (personal identification number) in order to access the AP's settings or to associate a new device with the network. The problem is that the PIN can be easily cracked through a brute force attack, which means simply trying numerous possible character combinations to find the correct combination. This gives the attacker access to the network's WPA2 key.
When deciding antenna types, why might the use of an omnidirectional antenna be inadvisable?
You might think that omnidirectional antennas would nearly always be the best choice when setting up Wi-Fi coverage. The idea is to place the AP in the center of its coverage area, then send the signal out in all directions. However, in many situations, installing unidirectional antennas instead will enhance a signal's availability, directing the signal right where you need it while not wasting a signal in areas where you don't. For example, suppose a company installs an omnidirectional antenna near a factory's 30-foot high ceiling. Because the antenna's signal is broadcast in all directions from its location, distributing its signal strength in a spherical shape, the best possible signal would only be available to workers who could walk on the ceiling-obviously, that's not a viable situation. To be useful, the signal needs to be directed down to the floor. A unidirectional antenna, in this case, can be positioned up high and pointed down to create a dome-shaped coverage that spreads out as it nears the plant floor
Healing messages are a feature of what smart home protocol?
Z-Wave
In IEEE terminology, a group of stations that share an access point are said to be part of which of the following?
basic service set
What special signal is issued periodically from an AP and contains the network transmission rate and service set identifier (SSID), as well as other information needed for a computer to associate with the AP?
beacon frame
Upon connecting to a Wi-Fi network, you're redirected to a login screen and a request to accept terms of service before being connected. What is this an example of?
captive portal
Which 802.11 frame type is related to medium access and data delivery, and includes ACK and RTS/CTS frames?
control frames
In the classful addressing scheme, what range of network addresses is considered a Class B?
.128.0.x.y to 191.255.x.y
What is the maximum supported throughput of a CAT6 cable?
10 Gbps
What is the fastest Ethernet standard that can possibly be used on twisted-pair cabling?
10GBase-T
By default, what is the MTU size on a typical Ethernet network?
1500 bytes
If the VLAN tag is present in an Ethernet frame, what is the maximum frame size?
1522 bytes
When terminating an Ethernet cable, about how far should the cable sheath extend into the plug?
3/8 inch
What is the minimum category of UTP cable required in order to support Gigabit speeds?
Cat 5e
Why are the Class D and Class E IPv4 address ranges not available for general use?
Class D addresses begin with octets 224 through 239 and are used for multicast transmissions, in which one host sends messages to multiple hosts. An example of this is when a host transmits a videoconference over the Internet to multiple participants. Class E addresses, which begin with 240 through 254, are reserved for research.
How is an IPv6 address written and displayed?
IPv6 addresses are written and displayed as follows: * An IPv6 address has 128 bits that are written as eight blocks (also called quartets) of hexadecimal numbers separated by colons, like this: 2001:0000:0B80:0000:0000:00D3:9C5A:00CC. * Each block is 16 bits. For example, the first block in the preceding IP address is the hexadecimal number 2001, which can be written as 0010 0000 0000 0001 in binary. * Leading zeroes in a four-character hex block can be eliminated. This means our sample IP address can be written as 2001:0000:B80:0000:0000:D3:9C5A:CC. * If blocks contain all zeroes, they can be eliminated and replaced by double colons (::). To avoid confusion, only one set of double colons is used in an IP address. This means our sample IP address can be written two ways: 2001::B80:0000:0000:D3:9C5A:CC or 2001:0000:B80::D3:9C5A:CC
How does IPv6 utilize Neighbor Discovery Protocol to detect neighboring devices?
IPv6 devices use NDP (Neighbor Discovery Protocol) in ICMPv6 messages to automatically detect neighboring devices, and to automatically adjust when neighboring nodes fail or are removed from the network. NDP eliminates the need for ARP and some ICMP functions in IPv6 networks, and is much more resistant to hacking attempts than ARP.
IPv6 has two different types of unicast addresses. How do these two types differ from each other?
IPv6 unicast addresses come in two types: * global addresses-Can be routed on the Internet and is similar to public IPv4 addresses. Most begin with the prefix 2000::/3, although other prefixes are being released. The /3 indicates that the first three bits are fixed and are always 001. * link local addresses-Can be used for communicating with nodes in the same link, and is similar to an autoconfigured APIPA address in IPv4. It begins with FE80::/10. The first 10 bits of the reserved prefix are fixed (1111 1110 10), and the remaining 54 bits in the 64-bit prefix are all zeroes. Therefore, a link local address prefix is sometimes written as FE80::/64. Link local addresses are not allowed past the local link or on the Internet.
The IP connectionless protocol relies on what other protocol to guarantee delivery of data?
TCP
Encrypted control of remote computers using the RDP protocol is accomplished using what port number?
TCP 3389
You have been awarded a contract for wiring a new federal building. What twisted-pair wiring standard must you use?
TIA/EIA 568A
What is the industry standard angle for an Angle Polished Connector (APC)?
8 degrees
How can a network switch be said to operate at Layer 4 of the OSI model?
A Layer 4 switch is capable of interpreting Layer 4 data. They operate anywhere between Layer 4 and Layer 7 and are also known as content switches or application switches. Among other things, the ability to interpret higher layer data enables switches to perform advanced filtering, keep statistics, and provide security functions. In general, however, a Layer 4 switch is still optimized for fast Layer 2 data handling.
What statement describes a transmission flaw that is occurring due to attenuation?
A customer modem is continuously losing signal due to large distance from the transmitting device.
In a DNS zone, what type of record holds the name-to-address mapping for IPv6 addresses?
AAAA record
ARP tables might contain two different types of entries. What are they, and how are they created?
ARP tables can contain two types of entries: dynamic and static. Dynamic ARP table entries are created when a client makes an ARP request for information that could not be satisfied by data already in the ARP table; once received, the new information is recorded in the table for future reference. Static ARP table entries are those that someone has entered manually using the ARP utility. This ARP utility, accessed via the arp command in both Windows and Linux, provides a way of obtaining information from and manipulating a device's ARP table.
What are some of the basic functions of a network router?
Although any one router can be specialized for a variety of tasks, all routers can do the following: * Connect dissimilar networks, such as a LAN and a WAN, which use different types of routing protocols. * Interpret Layer 3 and often Layer 4 addressing and other information (such as quality of service indicators). * Determine the best path for data to follow from point A to point B. The best path is the most efficient route to the message's destination calculated by the router, based upon the information the router has available to it. * Reroute traffic if the path of first choice is down but another path is available.
Originally codified by ISO, what does the "intermediate system" in IS-IS (Intermediate System to Intermediate System) stand for?
An IS-IS capable network router
Originally codified by ISO, what does the "intermediate system" in IS-IS (Intermediate System to Intermediate System) stand for?
An IS-IS capable network router.
How might an organization configure a DNS server for use on their network?
An organization might utilize these four common types of DNS server configurations: * primary DNS server-The authoritative name server for the organization, which holds the authoritative DNS database for the organization's zones. This server is contacted by clients, both local and over the Internet, to resolve DNS queries for the organization's domains. * secondary DNS server-The backup authoritative name server for the organization. When a secondary DNS server needs to update its database, it makes the request to the primary server for the update; this process is called a zone transfer. * caching DNS server-A server that accesses public DNS data and caches the DNS information it collects. This server receives DNS queries from local network clients and works to resolve them by contacting other DNS servers for information. Caching DNS servers do not store zone files (which is why they must rely on their caches and resolution efforts), and therefore do not participate in zone transfers. * forwarding DNS server-An optional server that receives queries from local clients but doesn't work to resolve the queries. Typically, a forwarding server will maintain its own DNS cache from previous queries, and so it might already have the information the client needs. If not, the forwarding server forwards the query to another server to resolve. Several forwarding servers might be strategically placed throughout the organization's network to reduce network traffic on slow links.
What is the difference between bandwidth and throughput?
Bandwidth is the amount of data that could theoretically be transmitted during a given period of time. In an analogy, the bandwidth of a three-lane freeway is the number of vehicles that can pass a checkpoint in one minute when traffic is bumper-to-bumper and traveling at the maximum speed limit. In practice, that bandwidth never happens. Still, we could increase potential bandwidth by adding more lanes to the freeway. At the same time, consider that adding too many lanes for the amount of anticipated traffic, so that some lanes are never used, would be a waste of resources. Throughput is the measure of how much data is actually transmitted during a given period of time. In our analogy, throughput measures the actual traffic on the three-lane freeway that passes in one minute. Using all the available bandwidth results in more accidents and traffic jams than if bandwidth exceeds actual throughput by a little. However, this beneficial effect is limited-providing a lot more potential bandwidth than actual throughput does not achieve additional improvement in performance unless you need to account for regular spikes in traffic.
An IPv6 address consists of 128 bits that are written as 10 blocks of hexadecimal numbers separated by colons.
False
DNS follows a centralized database model, allowing for easier management of DNS records.
False
ICANN is responsible for restrictions on use of the .com, .org, and .net TLDs.
False
IPv4 and IPv6 use the same packet format.
False
Routing Information Protocol (RIP) is an interior gateway protocol that uses a link-state algorithm.
False
TCP uses a four-step process called a four-way handshake to establish a TCP connection.
False
The 1024 - 65535 range of ports is also known as the "well-known" range.
False
The CTRL + S key combination can be used to stop an actively running command
False
The CTRL + S key combination can be used to stop an actively running command.
False
The FTP protocol utilizes UDP, while TFTP uses TCP for data transmission.
False
The ST and SC fiber connectors are the most commonly found connectors due to their smaller sizes.
False
UDP provides error checking, but not sequencing
False
What is a fiber distribution panel, and how is it used?
It is usually a case on a rack where fiber cables converge, connect with each other, and connect with fiber optic terminal equipment from the ISP. Splices at the FDP (or elsewhere on the network) might be accomplished by joining two fiber cables in a permanent bond, or various connectors might be used to create temporary splices. The transition between single mode fiber and multimode fiber cabling might also occur at an FDP.
What statement correctly describes "jitter"?
Jitter is what happens when packets experience varying amounts of delay and arrive out of order.
Which of the following statements about fiber-optic cabling is accurate?
Light experiences virtually no resistance when traveling through glass.
Which statement accurately describes what near end crosstalk (NEXT) is?
NEXT is crosstalk that occurs between wire pairs near the source of a signal.
What are the different transceiver types that have made the GBIC obsolete?
Newer transceivers that have made the GBIC obsolete include: * SFP (small form-factor pluggable)-Provides the same function as GBICs and is more compact, allowing more ports per linear inch. Also known as mini GBICs or SFP GBICs. Typically used for 1 Gbps connections, but theoretically capable of 5 Gbps. * XFP (10 Gigabit small form-factor pluggable)-Supports up to 10 Gbps and is slightly larger than SFP with lower power consumption than SFP+. * SFP+-Developed later than XFP and is the same module size as SFP; theoretical maximum transmission speed is 16 Gbps. * QSFP (quad small form-factor pluggable)-Complies with the 802.3ba standard, squeezing four channels in a single transceiver and supporting data rates up to 40 Gbps (4 x 10 Gbps). * QSFP+-Generally the same technology as QSFP while supporting data rates over 40 Gbps. Highest speed format currently is QSFP28 with a total theoretical maximum data rate of 112 Gbps (4 x 28 Gbps). * CFP (centum form-factor pluggable)-Intended for 100-Gbps network connections, with each succeeding generation (CFP, CFP2, CFP4) becoming smaller and more energy-efficient. Centum is Latin for 100.
In the DNS hierarchy, where is information about how to find the top-level domain servers held?
On the DNS root servers.
When tracing a wire, how do you utilize a toner and probe kit?
Place the tone generator at one end of a wire using the appropriate connector. Swipe the tone locator over each of the terminations you suspect to be the other end of that wire. You can verify the location of the wire's termination when you hear the tone. Work by trial and error, guessing which termination corresponds to the wire over which you've generated a signal until the tone locator indicates the correct choice.
What are the three different types of port number ranges as defined by IANA?
Port numbers range from 0 to 65535 and are divided by IANA into three types: * well-known ports-Range from 0 to 1023 and are assigned by IANA to widely used and well-known utilities and applications, such as Telnet, FTP, and HTTP. * registered ports-Range from 1024 to 49151 and can be used temporarily by processes for nonstandard assignments for increased security. Default assignments of these registered ports must be registered with IANA. * dynamic and private ports-Range from 49152 to 65535 and are open for use without restriction.
What statement regarding the Power Over Ethernet standards is inaccurate?
Power over Ethernet requires CAT6 or better copper cable.
How are routing paths determined?
Routing paths are determined in one of two ways: * static routing-A network administrator configures a routing table to direct messages along specific paths between networks. For example, it's common to see a static route between a small business and its ISP. However, static routes can't account for occasional network congestion, failed connections, or device moves, and they require human intervention. * dynamic routing-A router automatically calculates the best path between two networks and accumulates this information in its routing table. If congestion or failures affect the network, a router using dynamic routing can detect the problems and reroute messages through a different path. When a router is added to a network, dynamic routing ensures that the new router's
Which of the following statements correctly describes the SFP+ transceiver?
SFP+ is the same size as SFP, and supports a theoretical maximum transmission speed of 16 Gbps.
Which of the following protocols is used as a signaling protocol for the initial connection between hosts, but does not participate in data transfer during the session?
SIP
What is the difference between single mode fiber and multimode fiber, and how do they compare?
SMF (single mode fiber) consists of a narrow core of 8 to 10 microns in diameter. Laser-generated light travels a single path over the core, reflecting very little. Because it reflects little, the light does not disperse as the signal travels along the fiber. This continuity allows SMF to accommodate the highest bandwidths and longest distances (without requiring repeaters) of all network transmission media. MMF (multimode fiber) contains a core with a larger diameter than SMF, usually 50 or 62.5 microns, over which many pulses of light generated by a laser or LED light source travel at various angles. Signals traveling over multimode fiber experience greater attenuation than those traversing single mode fiber. Therefore, MMF is not suited to distances longer than a few kilometers. On the other hand, MMF is less expensive to install and, therefore, typically used to connect routers, switches, and servers on the backbone of a network or to connect a desktop workstation to the network.
What are some examples of routing metrics that can be used to determine the best path for a network?
Some examples of routing metrics used to determine the best path may include: * Hop count, which is the number of network segments crossed * Theoretical bandwidth and actual throughput on a potential path * Delay, or latency, on a potential path, which results in slower performance * Load, which is the traffic or processing burden sustained by a router in the path * MTU, which is the largest IP packet size in bytes allowed by routers in the path without fragmentation (excludes the frame size on the local network) * Routing cost, which is a value assigned to a particular route as judged by the network administrator; the more desirable the path, the lower its cost * Reliability of a potential path, based on historical performance * A network's topology
What are the different categories of routers, and how do they compare?
Some of the different categories of routers are as follows: * Core routers, also called interior routers, are located inside networks within the same autonomous system. An AS (autonomous system) is a group of networks, often on the same domain, that are operated by the same organization. An AS is sometimes referred to as a trusted network because the entire domain is under the organization's control. Core routers communicate only with routers within the same AS. * Edge routers, or border routers, connect an autonomous system with an outside network, also called an untrusted network. For example, the router that connects a business with its ISP is an edge router. * Exterior router refers to any router outside the organization's AS, such as a router on the Internet backbone. Sometimes a technician might refer to her own edge router as an exterior router because it communicates with routers outside the AS. But keep in mind that every router communicating over the Internet is an edge router for some organization's AS, even if that organization is a large telecommunications company managing a portion of the Internet backbone.
There are several interior gateway protocols, but only one current exterior gateway protocol. What is this protocol, and what characteristics does it have?
The Border Gateway Protocol (BGP) is the only current exterior gateway protocol, and has been dubbed the "protocol of the Internet." Whereas OSPF and IS-IS scouting parties only scout out their home territory, a BGP scouting party can go cross-country. BGP spans multiple autonomous systems and is used by edge and exterior routers on the Internet. Here are some special characteristics of BGP: * path-vector routing protocol-Communicates via BGP-specific messages that travel between routers over TCP sessions. * efficient-Determines best paths based on many different factors. * customizable-Can be configured to follow policies that might, for example, avoid a certain router, or instruct a group of routers to prefer one particular route over other available routes
You have been tasked with maintaining a network that is jumbo frame enabled. What does this mean?
The MTU for the network can be as high as 9198 bytes.
How is the TTL (Time to Live) field utilized in IPv4?
The TTL field indicates the maximum duration that the packet can remain on the network before it is discarded. Although this field was originally meant to represent units of time, on modern networks it represents the number of times a packet can still be forwarded by a router, or the maximum number of router hops it has remaining.The TTL for packets varies and can be configured; it is usually set at 32 or 64. Each time a packet passes through a router, its TTL is reduced by 1. When a router receives a packet with a TTL equal to 0, it discards that packet and sends a TTL expired message via ICMP back to the source host.
How can you determine the manufacturer of a NIC card based on the MAC address?
The first 24 bits, known as the Organizationally Unique Identifier, identify the manufacturer.
In the event of a duplicate MAC address shared by two hosts on a switched network, what statement is accurate?
The hosts will still send and receive traffic, but traffic may not always reach the correct destination.
What is the biggest limiting factor on fiber-optic cable length?
The maximum length limitation is due primarily to optical loss, or the degradation of the light signal after it travels a certain distance away from its source (just as the light of a flashlight dims after a certain number of feet). Optical loss accrues over long distances and grows with every connection point in the fiber network. Dust or oil in a connection (for example, from people handling the fiber while splicing it) can further exacerbate optical loss.
What are the two different variations of network address translation (NAT)?
The two variations of NAT are: * SNAT-Using SNAT (Static Network Address Translation or Source Network Address Translation), the gateway assigns the same public IP address to a host each time it makes a request to access the Internet. Small home networks with only a single public IP address provided by its ISP use SNAT. * DNAT or Destination NAT-Using DNAT (Destination Network Address Translation), hosts outside the network address a computer inside the network by a predefined public IP address. When a message sent to the public IP address reaches the router managing DNAT, the destination IP address is changed to the private IP address of the host inside the network. The router must maintain a translation table of public IP addresses mapped to various hosts inside the network.
What are the two different types of DNS requests?
There are two types of DNS requests: * recursive query-A query that demands a resolution or the answer "It can't be found." For example, the initial request the resolver makes to the local server is a recursive query. The local server must provide the information requested by the resolver, as in "The buck stops here." * iterative query-A query that does not demand resolution. For example, when the local server issues queries to other servers, the other servers only provide information if they have it.
How do routers create a broadcast domain boundary?
They do not forward broadcast traffic.
A hexadecimal number is a number written in the base 16 number system.
True
At the root level of the DNS hierarchical structure, 13 clusters of root servers hold information used to locate TLD servers.
True
Each organization that provides host services on the public Internet is responsible for providing and maintaining DNS authoritative servers for public access.
True
IP is an unreliable, connectionless protocol, as it does not establish a session to send its packets.
True
In general, a Layer 3 or Layer 4 switch is still optimized for fast Layer 2 data handling.
True
What multiplexing technology lowers cost by spacing frequency bands wider apart to allow for cheaper transceiver equipment?
coarse wavelength division multiplexing
Utilizing time slots that are adjusted according to priority and need is an example of what type of multiplexing on copper lines?
statistical time division multiplexing
When viewing the pinout for T568B, what is the correct order of wire colors, starting at pin 1?
white/orange, orange, white/green, blue, white/blue, green, white/brown, brown