Ccna certification Practice Tests

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 56.  D.  The last router will send an ICMP packet back to the originating host, which has 

the result code of destination unreachable. The router will discard the packet, but a 

notification is still sent back to the originating host. The router will not change the TTL of 

the packet; it will just drop the packet and notify the originating host. The router will not 

bother with sending the original packet back to the originating host.

 57.  B.  A routing loop occurs when packets are routed between two or more routers and never 

make it to their destination. Routing loops can occur with more than two routers; it is in 

effect making the packet travel in a loop till its TTL expires. When packets are routed out 

one interface and come back in on a different interface, this is considered asynchronous 

routing and not typical of a routing loop. Packets reaching the expiry TTL could mean 

that there are too many hops to the destination network, but not that a routing loop is 

occurring. Packets being routed via an inefficient path is not a symptom of a routing loop.

 58.  A.  Open Shortest Path First (OSPF) is a link-state protocol. A link-state protocol tracks 

the state of a link between two routers and chooses the most efficient routes based upon 

the shortest path. Routing Information Protocol (RIP) is a distance-vector protocol. 

Enhanced Interior Gateway Routing Protocol (EIGRP) is considered a hybrid protocol. 

Interior Gateway Routing Protocol (IGRP) is a distance-vector protocol.

 59.  A.  Dynamic routes are stored in RAM. When the power is taken away from a router, all 

routes must be repopulated by neighboring routers. Flash is where the IOS of the router 

is stored. The startup configuration is stored in non-volatile random-access memory 

(NVRAM). The running configuration is stored in RAM along with tables such as 

dynamic routes.

 60.  A.  Latency is lower with SVI inter-VLAN routing because of the use of ASICs. This is 

usually why IVR switches are more expensive. Latency is not higher because the SVI inter-

VLAN routing uses ASICs. SVI inter-VLAN routing is not always a cheaper alternative 

to router on a stick (ROAS) because of licensing and the requirement of a layer 3 switch. 

Bandwidth is not limited like ROAS and is usually substantially higher, which is one of the 

main motivations to use SVI inter-VLAN routing.

 61.  C.  The lack of scalability of ROAS is a major disadvantage. It does not scale well when a 

large number of VLANs are configured. ROAS can be used with Inter-Switch Link (ISL) 

protocol for VLAN support. With 802.1Q or ISL trunking, you can tie several VLANs to 

a physical port. All dynamic routing protocols are supported with ROAS.

 62.  A.  The use of VLANs requires a unique IP network for each VLAN. This is how 

broadcast domains are increased, since all VLANs are behind a router interface (default 

gateway). IVR does not reduce the number of broadcast domains; it increases the number 

of broadcast domains. You’ll have several different VLANs in which you can broadcast 

as the scale of your network grows. IVR supports access control lists (ACLs) because you 

are creating network interfaces as you add VLANs. IVRs promote the use of subnetting 

because you need a unique IP network for each VLAN.

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