Network+ Guide to Networks (7th edition) chapter 3

Which of the following is not a task handled by a router?

A router forwards broadcasts over the network.

What parameter can be combined with the traceroute command to instruct it to use ICMP echo requests instead of UDP datagrams?​

-I

What netstat command option lists only current connections, including IP addresses and port numbers?

-n

By default, the pathping command sends how many pings per hop?​

100

A modern ASN consists of how many bits?

32

Messages are sent to a default gateway—a router or Layer 3 switch—when their destination is not on the host's local network.

A default route is a backup route when no other route can be determined. The default route points to the gateway of last resort, which is the router assigned to receive unroutable messages from other routers.

ICMP (Internet Control Message Protocol) is a Network layer core protocol that reports on the success or failure of data delivery, although it does not correct the

errors that it detects. On IPv6 networks, ICMPv6 detects and reports data transmission errors, discovers other nodes on a network, and manages multicasting.

As a network support technician, you only need to know how to support IPv6. t/f

false

UDP provides error checking, but not sequencing.​ t/f

false

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 is NOT one of the three characteristics of TCP in its role as a reliable delivery protocol?​ Selected Answer: Incorrecta. ​Flow Control a. ​Flow Control b. ​Framing c. ​Connection-oriented Protocol d. ​Sequencing and checksums

framing

Recall that the first half of a MAC address can be used to

identify the manufacturer of that NIC, which may help you in identifying a NIC among other NICs

A router is a multiport device that can connect dissimilar LANs and WANs running at different transmission speeds, using a variety of

protocols. Routers interpret logical addresses and determine the best path between nodes. They operate at the Network layer (Layer 3) or higher of the OSI model.

Which of the following is not a task handled by a router? a. ​A router can reroute traffic if the path of first choice is down but a second path is available. b. ​A router can connect dissimilar networks. c. ​A router can interpret Layer 3 and often Layer 4 addressing. d. ​A router forwards broadcasts over the network.

A router forwards broadcasts over the network.

IP (Internet Protocol) belongs to the Network layer of the OSI model and provides information about how and where data should be delivered

ARP (Address Resolution Protocol) belongs to the Data Link layer of the OSI model. It obtains the MAC (physical) address of a host, or node, and then creates a local database that maps the IP (logical) address to the host's MAC (physical) address.

ARP (Address Resolution Protocol) works in conjunction with IPv4 to discover the MAC (physical) address of a host or node on the local network and to maintain a database that maps IP addresses to MAC addresses on the local network. ARP is a Layer 2 protocol that uses IP in Layer 3, and operates only within its local network bound by routers.

ARP relies on broadcasting, which transmits simultaneously to all nodes on a particular network segment. For example, if one node needs to know the MAC address of another node on the same network, the first node issues a broadcast message to the network, using ARP, that essentially says,

IS-IS uses virtually the same methods as OSPF to calculate best paths, is less common, and is limited to interior routers.

BGP (Border Gateway Protocol), designed primarily for routing over Internet backbones, uses the most complex best-path calculation of all the commonly used routing protocols. It's considered an exterior routing protocol.

What field in an IPv4 packet informs routers the level of precedence they should apply when processing an incoming packet?

Differentiated Services (DiffServ)

What protocol replaces ARP, IGMP, and ICMPv4 on IPv6 based networks?​

ICMPv6

What IPv4 protocol handles multicasting for tasks such as videoconferencing or teleconferencing?​

IGMP​

OSPF (Open Shortest Path First

IGP and a link-state routing protocol used on interior or border routers. It was introduced as an improvement to RIP and can coexist with RIP (or RIPv2) on a network. Unlike RIP, OSPF imposes no hop limits

They are typically used as part of a network's backbone and are not appropriate on a LAN.

In general, however, Layer 4, Layer 3, and Layer 2 switches are all optimized for fast Layer 2 data handling.

and provide security functions. The features of Layer 3 and Layer 4 switches vary widely depending on the manufacturer and price and can cost three times more than

Layer 2 switches. This variability is exacerbated by the fact that key players in the networking trade have not agreed on standards for these switches

Layer 4 switches also exist and are 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,

On IPv4 networks, IGMP (Internet Group Management Protocol or Internet Group Multicast Protocol) operates at the Network layer of the OSI model to manage multicasting. Unlike a broadcast transmission, a multicast transmission does not necessarily issue transmissions to every node on a segment.

Multicasting can, for example, be used for teleconferencing or videoconferencing over the Internet. Routers use IGMP to determine which nodes belong to a certain multicast group and to transmit data to all nodes in that group. Network nodes use IGMP to join or leave multicast groups at any time.

To determine the best path, routers communicate with each other through routing protocols, including RIP, RIPv2, OSPF, IS-IS, and BGP. Different routing protocols use different algorithms and routing metrics to choose the best path.

Routing metrics may factor in the number of hops between nodes, throughput, delay, MTU, cost, load, and reliability.

"Will the computer with the IP address 1.2.3.4 please send me its MAC address?" The node that has the IP address 1.2.3.4 then transmits a reply that contains the physical address of the destination host.

The database of IP-to-MAC address mappings is called an ARP table (also called an ARP cache) and is kept on a computer's hard drive. Each OS can use its own format for the ARP table.

A routing table is a database that maintains information about where hosts are located and the most efficient way to reach them. A router relies on its routing table to identify which

router is the next hop to reach a particular destination host. The routing table contains IP addresses and network masks that identify a network that a host or another router belongs to.

​What command can be used on a Cisco router to view the routing table?

show ip route

In a TCP segment, what field indicates how many bytes the sender can issue to a receiver while acknowledgement for the segment is outstanding?​

sliding window

Multilayer Switches. Layer 3 switch

switch that is capable of interpreting Layer 3 data and works much like a router: It supports the same routing protocols and makes routing decisions. Layer 3 switches were designed to work on large LANs, similar to interior routers, except they're faster and less expensive.

Static routing is a technique in which a network administrator configures a routing

table to direct messages along specific paths between networks.

Most networks primarily use dynamic routing, butmay include some static routing to indicate, for example, a gateway of last resort, which is

the router that accepts all unroutable messages from other routers.When a router cannot determine

The primary difference is the way the hardware is built, but, in fact, it's often hard

to distinguish between a Layer 3 switch and a router. In some cases, the difference comes down to what the manufacturer has decided to call the device in order to improve sales.

IP is an unreliable, connectionless protocol.​ t/f

true

On IPv4 networks, IGMP operates at the Network layer of the OSI model to manage multicasting. t/f

true

Static routes are appropriate in certain situations, such as the static route between a small business and its ISP. However, static routes

used to traverse several networks don't account for occasional network congestion, failed connections, or device moves, and they require human intervention.

IS-IS (Intermediate System to Intermediate System

uses a best-path algorithm similar to OSPF's and was originally codified by ISO, which referred to routers as "intermediate systems,

​Which network routing protocol is a path vector protocol that sends updates between routers using TCP?

​BGP

What is NOT one of the three characteristics of TCP in its role as a reliable delivery protocol?​

​Framing

TCP (Transmission Control Protocol) is an OSI Transport layer, connection-oriented protocol that requires a connection to be established between communicating nodes before it will transmit data. TCP provides reliability through checksum, flow control, and sequencing information.

UDP (User Datagram Protocol), like TCP, is a Transport layer protocol. UDP is a connectionless service and offers no delivery guarantees. But UDP is more efficient than TCP and useful in applications that require fast data transmission, such as videoconferencing.

OSPF (Open Shortest Path First) is a link-state routing protocol used on interior or border routers. It was introduced as an improvement to RIP and can coexist with RIP (or RIPv2) on a network.

Unlike RIP, OSPF imposes no hop limits on a transmission path. Also, OSPF uses a more complex algorithm for determining best paths than RIP uses.

RIP (Routing Information Protocol), a distance-vector routing protocol, is the slowest and least secure routing protocol and limits transmissions to 15 hops. RIPv2 makes up for some of the original RIP's overhead

and security limitations, but its forwarding ability is limited to 15 hops. RIP belongs to the IGP (interior gateway protocol) category of protocols that can forward data only within an autonomous LAN.

Static ARP table entries

are those that someone has entered manually using the ARP utility. This ARP utility, accessed via the arp command from a Windows command prompt or a UNIX or Linux shell prompt,

ASN

autonomous system number now consists of 32 bits, and they are assigned by IANA

Dynamic routing, on the other hand, automatically calculates the best path between two networks and accumulates this information in the 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. By default, when a router is added to a network, dynamic routing ensures that the new router's routing tables are updated.

BGP (Border Gateway Protocol

can span multiple autonomous systems and is used by border and exterior routers on the Interne

pathping

combines elements of both ping and tracert to provide deeper information about network issues along a route. It sends multiple pings to each hop along a route, then compiles the information into a single report.

Border routers (or gateway routers)

connect an autonomous system with an outside network. For example, the router that connects a business with its ISP is a border router.

What routing protocol criteria is defined as the time it takes to recognize a best path change in the event of a network outage?

convergence time

Dynamic ARP table entries are created when a client makes an ARP request that could not be satisfied by data

created when a client makes an ARP request that could not be satisfied by data already in the ARP table.

Exterior routers

direct data between autonomous systems. Routers that operate on the Internet backbone are considered exterior routers. An exterior router can also be a border or gateway router if it stands between an autonomous system and an outside network.

Interior routers

direct data between networks within the same autonomous system.

Static routing is a technique in which a network administrator programs a router to use specific paths between nodes. Dynamic routing automatically calculates the best path between two nodes and accumulates this information

in a routing table. If congestion or failures affect the network, a router using dynamic routing can detect the problems and reroute data through a different path. Most modern networks use dynamic routing.

autonomous system (AS)

is a group of networks, often on the same domain, that are operated by the same organization. For example, Cengage, the company that published this book, might have several LANs that all fall under the cengage.com domain, with each LAN connected to the others by interior routers.

​At what layer of the OSI model would a TCP or UDP header be added to a payload?

layer 4

determined. The routers will continue resorting to default routes until the hop

limit is depleted or until a path can be determined and the destination is reached,whichever comes first

What type of routing protocol enables routers to communicate beyond neighboring routers, allowing each router to create a map of an entire network?​

link state

a path to a message's destination, the router sends the message along a default route, usually to another router. This

next router will also attempt to determine a path for the message, but is also programmed with a default route if a path cannot be

The IP connectionless protocol relies on what other protocol to guarantee delivery of data?

​TCP

​The IP connectionless protocol relies on what other protocol to guarantee delivery of data?

​TCP

What happens when a router receives a packet with a TTL of 0?​

​The router drops the packet and sends an ICMP TTL expired message back to the host.

When viewing the routing table on a UNIX system, what flag indicates if a route is a usable route?​

​U

What TCP field below allows the receiving node to determine whether a TCP segment is corrupted during transmission?​

​checksum

In a TCP segment, what field indicates how many bytes the sender can issue to a receiver while acknowledgement for the segment is outstanding?​

​sliding window