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CCNA FAQ: IP Routing Static and Connected

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CCNA FAQ: IP Routing Static and Connected

Q1. A PC user turns on her computer, and as soon as the computer is up and working, she opens a web browser to browse http://www.ciscopress.com. Which protocol(s) would definitely not be used by the PC during this process?
a. DHCP
b. DNS
c. ARP
d. ICMP

Explanation:D. The host might need to use Dynamic Host Configuration Protocol (DHCP) to acquire an IP address, and it would likely use Domain Name System (DNS) to resolve http://www.ciscopress.com into an IP address. It would also use Address Resolution Protocol (ARP) to find the default gateway’s MAC address, because the ARP cache would have been cleared as part of the boot process. ptg6876495 Chapter 5 673

Q2. A PC user turns on her computer, and as soon as the computer is up and working, she opens a command prompt. From there, she issues the ping 2.2.2.2 command, and the ping shows 100 percent success. The PC’s IP address is 1.1.1.1 with mask 255.255.255.0. Which of the following settings would be required on the PC to support the successful ping?
a. The IP address of a DNS server
b. The IP address of a default gateway
c. The IP address of an ARP server
d. The IP address of a DHCP server

Explanation:B. The ping 2.2.2.2 command does not use a host name, so no DNS server is required. A DHCP client does not need to know the DHCP server’s IP address to use DHCP. There’s no such thing as an ARP server. However, to send the packet to another subnet, the PC needs to know the IP address of its default gateway.

Q3. Router 1 has a Fast Ethernet interface 0/0 with IP address 10.1.1.1. The interface is connected to a switch. This connection is then migrated to use 802.1Q trunking. Which of the following commands could be part of a valid configuration for Router 1’s Fa0/0
interface? (Choose two answers.)
a. interface fastethernet 0/0.4
b. dot1q enable
c. dot1q enable 4
d. trunking enable
e. trunking enable 4
f. encapsulation dot1q

Answer: A and F

Q4. A router is configured with the no ip subnet-zero global configuration command. Which of the following interface subcommands would not be accepted by this router?
a. ip address 10.1.1.1 255.255.255.0
b. ip address 10.0.0.129 255.255.255.128
c. ip address 10.1.2.2 255.254.0.0
d. ip address 10.0.0.5 255.255.255.252

Explanation:C. With the no ip subnet-zero command configured, the router will not allow any interfaces to be configured with an IP address in the zero subnet. Of the listed answers, subnet 10.0.0.0 255.254.0.0 is a zero subnet, with a range of addresses from 10.0.0.1 to 10.1.255.254. The ip address 10.1.2.2 255.254.0.0 command would be rejected.

Q5. Which one of the following answers describes an action or event that most directly causes a router’s show ip route command to list an identifying code of S beside a route? (Choose three answers.)
a. The IP address must be configured on an interface.
b. The router must receive a routing update from a neighboring router.
c. The ip route command must be added to the configuration.
d. The ip address command must use the special keyword.
e. The interface must be up and up.

Explanation:A, C, E. The ip route command must define the static route; the “s” in the output means “static.” However, the interface referenced or implied by the route must also be up/up, and IP must be enabled on the outgoing interface as well, typically with the configuration of the ip address command.

Q6. Which of the following commands correctly configures a static route?
a. ip route 10.1.3.0 255.255.255.0 10.1.130.253
b. ip route 10.1.3.0 serial 0
c. ip route 10.1.3.0 /24 10.1.130.253
d. ip route 10.1.3.0 /24 serial 0

Answer: A. The correct syntax lists a subnet number, then a subnet mask in dotted decimal form, and then either an outgoing interface or a next-hop IP address.

Q7. Which of the following is affected by whether a router is performing classful or classless routing?
a. When to use a default route
b. When to use masks in routing updates
c. When to convert a packet’s destination IP address to a network number
d. When to perform queuing based on the classification of a packet into a particular queue

Answer: A

Q8. A router has been configured with the ip classless global configuration command. The router receives a packet destined to IP address 168.13.4.1. The following text lists the contents of the router’s routing table. Which of the following is true about how this router forwards the packet? Gateway of last resort is 168.13.1.101 to network 0.0.0.0
168.13.0.0/24 is subnetted, 2 subnets C 168.13.1.0 is directly connected, FastEthernet0/0 R 168.13.3.0 [120/1] via 168.13.100.3, 00:00:05, Serial0.1
a. It is forwarded to 168.13.100.3.
b. It is forwarded to 168.13.1.101.
c. It is forwarded out interface Fa0/0, directly to the destination host.
d. The router discards the packet

Explanation:B. With classless routing enabled, the router uses the default route if no other routes are matched. The line beginning “Gateway of last resort . . .” lists the IP address of the next-hop router, 168.13.1.101, which will be used as the default route.

Q9. What are the Layer 2 and Layer 3 characteristics of a packet destined for a network on a remote segment?

Answer: When a packet is destined for a remote network, the Layer 3 source address is the workstation or device that is sending the traffic. The destination Layer 3 address is the IP address of the destination device. At Layer 2, the source address is the MAC address of the sending workstation or device. The destination Layer 2 address, however, is the MAC address of the default gateway. The default gateway is the routing device on the local segment that is responsible for forwarding packets from the local segment to remote networks.

Q10. Why would you use a static route versus a routing protocol?

Answer: Static routes are used primarily in stub networks or when the administrator wishes to have complete control over the routing decisions of their routing devices. Routing protocols are used in complex networks with multiple paths to a destination. Unlike static routes, routing protocols can dynamically react to topology changes in the internetwork.

Q11. What are the characteristics of distance vector routing protocols?

Answer: Distance vector routing protocols periodically send routing table updates to their directly connected neighbors regardless of whether there is a change in the topology. These routine routing updates contain the contents of the entire routing table.

Q12. What are the characteristics of link-state routing protocols?

Answer: Link-state routing protocols initially discover their neighbors and retain that information in a neighbor table. Information about all possible routes is exchanged between these neighbors and stored in a router’s topology table. After the initial exchange of information, link-state routers periodically send hello messages as opposed to full routing updates. With the knowledge of all possible routes in the topology, the routers calculate the best route to each destination and place them in the routing table.

Q13. What is the difference between classful and classless routing protocols?

Answer: Classful routing protocols do not contain the subnet mask in the routing updates. Networks using classful routing protocols require that a FLSM design does not support discontiguous networks. Classless routing protocols updates contain the subnet mask that enables the network design to support VLSM and discontiguous networks.

Q14. Given the following output, on which interface will a packet destined for 192.168.1.34 /24 be routed?
ccna-faq-ip-routing-static-connected
ccna-faq-ip-routing-static-connected2
A. Serial 0/1
B. Serial 0/0
C. Fast Ethernet 0/0
D. None of the above

Answer: D. A packet destined for 192.168.1.34 /24 would require a network entry for 192.168.1.0 in the routing table. Because there isn’t an exact match for that network, the router sends it out the interface specified in a default route. This router does not have a default route configured, so the packet is dropped, and an ICMP destination unreachable is sent to the source. Answer A is incorrect because packets destined for the 10.0.0.0 /8 exit the serial 0/1 interface. Answer B is incorrect because packets destined for the 172.17.0.0 /16 exit the serial 0/0 interface. Answer C is incorrect because packets destined for the 172.16.0.0 /16 exit the Fast Ethernet 0/0 interface.

Q15. Your network designer subnetted the major classful network of 192.168.2.0 into varying-sized subnets throughout your network. Which routing protocol category should not be your choice of routing protocol?
A. Classful
B. IGP
C. Link-state
D. ODR

Answer: A. Because the network is designed with variable-length subnet masks, you should not use a classful routing protocol. B is incorrect because IGP routing protocols should be utilized inside your network. C is incorrect because link-state routing protocols support classless routing updates. D is incorrect because classless routing protocols support VLSM designs.

Q16. Which of the following is not a characteristic of link-state routing protocols?
A. Fast convergence
B. Broadcasts routing table
C. Keeps track of neighbors in table
D. Knows all possible routes

Answer: B. Link-state routing protocols do not broadcast their entire routing tables. They synchronize their topology table containing all possible routes with the neighbors they initially discover. Answers A, C, and D are all characteristics of link-state routing protocols.

Q16. Which of the following is not a subnet in the CIDR summary route 192.168.16.0 /21?
A. 192.168.16.0 /24
B. 192.168.20.0 /24
C. 192.168.24.0 /24
D. 192.168.23.0 /24

Answer: C. Because the summary route stole three bits from the default Class C (/24), you are summarizing 23 or eight networks. 192.168.16.0 is in an increment of 8, so that is the base network. The range of networks that are summarized extend to network 192.168.23.0 for a total of 8 networks Answers A, B, and D all fit in the range of networks that are summarized by the 192.168.16.0 /21 summary route.

Q17. What is the consequence of using the following command? Router(config)# ip route 0.0.0.0 0.0.0.0 192.168.10.2
A. The entry will show up in the routing table signified with an R.
B. This entry is configured in a Layer 2 switch to send traffic to a Layer 3 routing device.
C. 192.168.10.2 is the IP address of the router that advertised this network in the routing protocol update.
D. If there is not an exact match in the routing table, packets will be sent to 192.168.10.2.

Answer: D. The default route configured specifies that packets should be routed to the 192.168.10.2 next hop if there is not a specific match in the routing table. Answer A is incorrect because static route entries show up with the letter S in the routing table. Answer B is incorrect because by default this is a routing command that can be configured only in Layer 3 devices. IP default gateway is the command to configure a gateway of last resort for Layer 2 switches. Answer C is false because static routes are not advertised to other routers.

Q18. What is the consequence of using the following command? (Choose two)
Router(config)# ip route 192.168.20.4 255.255.255.0 10.1.1.1 3
A. The 3 at the end of the command signifies that it is a floating static route.
B. The 3 at the end of the command signifies the hops to get to the destination.
C. The destination network is incorrect, so this command will not work.
D. The default administrative distance for this command is 120.

Answer: A, C. The 3 at the end of the static route command overrides the default administrative distance of 1 for a static route. This is probably being used to create a floating static route in a redundant network. The command, however, does not work because you have an inconsistent subnet mask with the destination network. The network ID should reflect 192.168.20.0 or the subnet mask should be 255.255.255.252. Answer B is incorrect because the 3 represents the administrative distance. Answer D is incorrect because static routes have a default administrative distance of 1.

Q19. The network entry for 192.168.2.0 /24 is being advertised by RIP and OSPF. Which routing protocol displays the subnet in the routing table, and why?
A. OSPF because it has a lower metric
B. RIP because it is classful
C. OSPF because it has a lower administrative distance
D. RIP because it has a higher administrative distance

Answer: C. OSPF has a lower administrative distance than RIP (110 vs. 120), so that entry shows up in the routing table because the lower administrative distance is preferred over higher ones. Answer A is incorrect because the metric of OSPF applies only if the OSPF routing protocol has multiple pathways to the 192.168.2.0 network. Answer B is false because classful or classless is not a factor in decisions between routing sources. Answer D is incorrect because routing protocols with lower administrative distances are trusted over routing protocols with higher administrative distances.

Q20. Which of the following is not a reason to use static routes?
A. To minimize configuration in complex networks.
B. To get finer control of routing decisions.
C. Destination networks are stubs.
D. To conserve bandwidth.

Answer: A. Static routes require more configurations in a complex network because you have to configure a static route for each destination in every router. Answers B, C, and D are all valid reasons to use static routes.

Q21. Given the following entries in a routing table, on which interface will a packet destined for 10.4.0.1 exit?
ccna-faq-ip-routing-static-connected3
A. Fast Ethernet 0/0
B. Serial 0/1
C. Serial 0/0
D. None of the above

Answer: C. Because the OSPF entry has the longest match for the 10.4.0.1 network, you use that route out Serial 0/0. The interfaces in answers A and B conceivably could be used; however, the longest match rule states that when a packet has multiple possible network entries to use, the more specific subnet is used over the less specific. Because the serial interface has the longest match (the most specific subnet), that is the interface the packet destined for 10.4.0.1 will use.

Q22. Given the following entries in a routing table, which of the following are true? (Choose two)
RouterA> show ip route
…Ouput Omitted…
Gateway of last resort is 192.168.2.10 to network 0.0.0.0
C 172.16.0.0/16 is directly connected, FastEthernet0/0
10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
I 10.0.0.0/8 [100/8976] via 172.17.0.2, FastEthernet0/1
D 10.1.0.0/16 [90/2297856] via 192.168.1.10, Serial0/1
D 10.4.0.0/16 [90/2297856] via 192.168.1.10, Serial0/1
S* 0.0.0.0/0 [1/0] via 192.168.2.10, Serial0/0
A. A packet destined for 192.168.100.2 will exit Serial 0/0.
B. The metric for network 10.4.0.0/16 is 90.
C. The metric for network 10.0.0.0/8 is 8976.
D. The routing protocol for network 10.1.0.0 has an administrative distance of 100.

Answer: A, C. This routing table indicates that a default route is configured. Because there isn’t a match for 192.168.100.2 in the routing table, it is sent out Serial 0/0 as specified in the default route. The numbers in the brackets represent the administrative distance followed by the metric. Thus, the remaining correct statement is that the metric for the IGRP route for 10.0.0.0/8 is 8976. Answer B is false because the metric for the 10.4.0.0 /16 network is 2297856. Answer D is incorrect because the 10.1.0.0 /16 network is learned via EIGRP which has an administrative distance of 90

Q23. What command was used to generate the following output?
ccna-faq-ip-routing-static-connected-1

Answer: show ip route The ip route command is used to display the routing table of a router.

Q24. You are viewing the routing table and you see an entry 10.1.1.1/32. What legend code would you expect to see next to this route?
A. C
B. L
C. S
D. D

Answer: B. In the new 15 IOS code, Cisco defies a different route called a local route. Each has a /32 prefi defiing a route just for the one address.

Q25. Which of the following statements are true regarding the command ip route
172.16.4.0 255.255.255.0 192.168.4.2? (Choose two.)
A. The command is used to establish a static route.
B. The default administrative distance is used.
C. The command is used to configure the default route.
D. The subnet mask for the source address is 255.255.255.0.
E. The command is used to establish a stub network.

Answer: A, B. Although option D almost seems right, it is not; the mask is the mask used on the remote network, not the source network. Since there is no number at the end of the static route, it is using the default administrative distance of 1.

Q26. What destination addresses will be used by HostA to send data to the HTTPS server as shown in the following network? (Choose two.)
ccna-faq-ip-routing-static-connected-4
A. The IP address of the switch
B. The MAC address of the remote switch
C. The IP address of the HTTPS server
D. The MAC address of the HTTPS server
E. The IP address of RouterA’s Fa0/0 interface
F. The MAC address of RouterA’s Fa0/0 interface

Answer: C, F. The switches are not used as either a default gateway or other destination. Switches have nothing to do with routing. It is very important to remember that the destination MAC address will always be the router’s interface. The destination address of a frame, from HostA, will be the MAC address of the Fa0/0 interface of RouterA. The destination address of a packet will be the IP address of the network interface card (NIC) of the HTTPS server. The destination port number in the segment header will have a value of 443 (HTTPS).

Q27. Using the output shown, what protocol was used to learn the MAC address for 172.16.10.1?
ccna-faq-ip-routing-static-connected-5
A. ICMP
B. ARP
C. TCP
D. UDP

Answer: B. This mapping was learned dynamically which means it was learned through ARP.

Q28. Which of the following is called an advanced distance-vector routing protocol?
A. OSPF
B. EIGRP
C. BGP
D. RIP

Answer: B. Hybrid protocols use aspects of both distance vector and link state—for example, EIGRP. Although be advised that Cisco typically just calls EIGRP an advanced distance vector routing protocol. Do not be mislead by the way the question is worded. Yes, I know that MAC addresses are not in a packet. You must read the question for understanding of what they are really asking.

Q29. When a packet is routed across a network, the ______________ in the packet changes at every hop while the ____ does not.
A. MAC address, IP address
B. IP address, MAC address
C. Port number, IP address
D. IP address, port number

Answer: A. Since the destination MAC address is different at each hop, it must keep changing. The IP address which is used for the routing process does not.

Q30. Which statement is true regarding classless routing protocols? (Choose two.)
A. The use of discontiguous networks is not allowed.
B. The use of variable length subnet masks is permitted.
C. RIPv1 is a classless routing protocol.
D. IGRP supports classless routing within the same autonomous system.
E. RIPv2 supports classless routing.

Answer: B, E. Classful routing means that all hosts in the internetwork use the same mask and that only default masks are in use. Classless routing means that you can use variable length subnet masks (VLSMs).

Q31. Which two of the following are true regarding the distance-vector and link-state routing protocols? (Choose two.)
A. Link state sends its complete routing table out of all active interfaces at periodic time intervals.
B. Distance vector sends its complete routing table out of all active interfaces at periodic time intervals.
C. Link state sends updates containing the state of its own links to all routers in the internetwork.
D. Distance vector sends updates containing the state of its own links to all routers in the internetwork.

Answer: B, C. The distance-vector routing protocol sends its complete routing table out of all active interfaces at periodic time intervals. Link-state routing protocols send updates containing the state of their own links to all routers in the internetwork.

Q32. When a router looks up the destination in the routing table for every single packet it is called _____________ .
A. dynamic switching
B. fast switching
C. process switching
D. Cisco Express Forwarding

Answer: C. This is how most people see routers, and certainly they could do this type of plain ol’ packet switching in 1990 when Cisco released their very fist router and traffi was seriously slow, but not in today’s networks! This process involves looking up every destination in the routing table and fiding the exit interface for every packet.

Q33. What type(s) of route is the following? Choose all that apply.
S* 0.0.0.0/0 [1/0] via 172.16.10.5
A. Default
B. Subnetted
C. Static
D. Local

Answer: A, C. The S* shows that this is a candidate for default route and that it was confiured manually.

Q34. A network administrator views the output from the show ip route command. A network that is advertised by both RIP and EIGRP appears in the routing table flagged as an EIGRP route. Why is the RIP route to this network not used in the routing table?
A. EIGRP has a faster update timer.
B. EIGRP has a lower administrative distance.
C. RIP has a higher metric value for that route.
D. The EIGRP route has fewer hops.
E. The RIP path has a routing loop.

Answer: B. RIP has an administrative distance (AD) of 120, while EIGRP has an administrative distance of 90, so the router will discard any route with a higher AD than 90 to that same network.

Q35. Which of the following is NOT an advantage of static routing?
A. Less overhead on the router CPU
B. No bandwidth usage between routers
C. Adds security
D. Recovers automatically from lost routes

Answer: D. Recovery from a lost route requires manual intervention by a human to replace the lost route.

Q36. What metric does RIPv2 use to find the best path to a remote network?
A. Hop count
B. MTU
C. Cumulative interface delay
D. Load
E. Path bandwidth value

Answer: A. RIPv1 and RIPv2 only use the lowest hop count to determine the best path to a remote network.

Q37. The Corporate router receives an IP packet with a source IP address of 192.168.214.20 and a destination address of 192.168.22.3. Looking at the output from the Corp router, what will the router do with this packet?
ccna-faq-ip-routing-static-connected-15
A. The packet will be discarded.
B. The packet will be routed out of the S0/0 interface.
C. The router will broadcast looking for the destination.
D. The packet will be routed out of the Fa0/0 interface.

Answer: A. Since the routing table shows no route to the 192.168.22.0 network, the router will discard the packet and send an ICMP destination unreachable message out of interface FastEthernet 0/0, which is the source LAN from which the packet originated.

Q38. If your routing table has a static, an RIP, and an EIGRP route to the same network, which route will be used to route packets by default?
A. Any available route
B. RIP route
C. Static route
D. EIGRP route
E. They will all load-balance.

Answer: C. Static routes have an administrative distance of 1 by default. Unless you change this, a static route will always be used over any other dynamically learned route. EIGRP has an administrative distance of 90, and RIP has an administrative distance of 120, by default.

Q39. Which of the following is an EGP?
A. RIPv2
B. EIGRP
C. BGP
D. RIP

Answer: C. BGP is the only EGP listed.

Q40. Which of the following is an advantage of static routing?
A. Less overhead on the router CPU
B. No bandwidth usage between routers
C. Adds security
D. Recovers automatically from lost routes

Answer: D. Recovery from a lost route requires manual intervention by a human to replace the lost route. The advantages are less overhead on the router and network, as well as more security.

Q41. What command produced the following output?
ccna-faq-ip-routing-static-connected-19
A. show ip route
B. show interfaces
C. show ip interface brief
D. show ip arp

Answer: C. The show ip interface brief command displays a concise summary of the interfaces.

Q42. In the following command what does the 150 at the end of the command mean?
Router(config)#ip route 172.16.3.0 255.255.255.0 192.168.2.4 150
A. Metric
B. Administrative distance
C. Hop count
D. Cost

Answer: B. The 150 at the end changes the default administrative distance (AD) of 1 to 150.

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