Routing Fundamentals Practice Questions

Answers and explanations appear when you work through the set above.

1. What is the default administrative distance of an external EIGRP route?

   • 90
   • 110 (OSPF's default)
   • 170
   • 200

2. A Cisco IOS router with default administrative distances learns usable routes to 192.168.5.0/24 from both OSPF and RIP. Which route is installed and why?

   • The RIP route, because its hop count metric is simpler
   • The OSPF route: its AD of 110 is lower than RIP's 120
   • Both, and the router load balances between them
   • Neither, the conflict causes the router to drop the prefix

3. In the routing table entry O 192.168.20.0/24 [110/65] via 10.0.0.2, what does the value 65 represent?

   • The administrative distance
   • The metric: cumulative OSPF interface cost
   • The number of seconds since the route was learned
   • The outgoing interface number

4. A packet arrives for a destination that matches no entry in the routing table and no default route exists. What does the router do?

   • Floods the packet out every interface except the one it arrived on
   • Drop it, usually with ICMP unreachable
   • Buffers the packet until a matching route is learned
   • Forwards the packet to the nearest neighbor router

5. What is the administrative distance of a directly connected route, and why is it set to that value?

   • 0, because a directly attached network is the most trusted route source
   • 1, because directly attached and static routes have the same default AD
   • 90, to match EIGRP so the two can be compared
   • 255, so it is never preferred over a learned route

6. Which statement best describes the difference between the control plane and the data plane on a router?

   • The control plane forwards user packets while the data plane builds the routing table
   • Control builds tables; data forwards packets
   • They are two names for the same forwarding process
   • The control plane exists on multilayer switches but is absent on routers

7. A floating static route is configured as ip route 10.5.0.0 255.255.0.0 192.168.1.2 115 while OSPF also advertises 10.5.0.0/16. What is the effect?

   • The static route is used immediately because static routes always win
   • The static route backs up OSPF because AD 115 exceeds 110
   • The router alternates between the two routes every 30 seconds
   • The configuration is rejected because static routes cannot take a distance value

8. A router receives a packet with IPv4 TTL 1 for a remote destination. What happens when it attempts to forward it?

   • It broadcasts the packet on every other interface
   • It drops the packet and may send ICMP Time Exceeded
   • It forwards the packet unchanged
   • It increases TTL to two

9. A router has two installed equal-cost routes to the same prefix. What can it do with traffic for that prefix?

   • Send a copy of each packet to both next hops
   • Discard the prefix as ambiguous
   • Load-share across both next hops (ECMP)
   • Always choose the oldest route

10. A connected interface goes administratively down. What normally happens to its connected route?

    • It becomes a static route
    • It remains active until reboot
    • It is advertised as a default route
    • It is removed from the routing table

11. Two OSPF routes of the same type (both intra-area) reach the same prefix with costs 20 and 40. Which route is preferred?

    • The cost-20 path
    • The cost-40 path
    • Both regardless of cost
    • The route with the highest router ID

12. An IOS interface is assigned 192.0.2.1/24. Which routing-table entry identifies the address owned by the router itself?

    • An O 192.0.2.0/24 route
    • An L 192.0.2.1/32 route
    • A C 192.0.2.0/24 route only
    • An S 192.0.2.1/32 route