Exploring the Functions of Routing

Question 1

All directly connected networks are added to the routing table automatically. A newly deployed router, without any configured interfaces, has an empty routing table. The directly connected routes are added after you assign a valid IP address to the router interface, enable it with the no shutdown command, and when it receives a carrier signal from another device (router, switch, end device, and so on).

Answer 1

Directly Connected Networks

Question 2

Identifies how the route was learned. Directly connected interfaces have two route source codes. “C” identifies a directly connected network. “L” identifies the local IPv4 address assigned to the router’s interface.

Answer 2

Route source

Question 3

For directly connected networks, the destination networks are local to the router. The destination network address is indicated with network address and subnet mask in the form of the prefix. Note that “L” entries, which identify the local IPv4 address of the interface, have a prefix of /32.

Answer 3

Destination network

Question 4

Identifies the exit interface to use when forwarding packets to the destination network.

Answer 4

Outgoing interface

Question 5

Dynamic routing protocols are used by routers to share information about the reachability and status of remote networks. A dynamic routing protocol allows routers to automatically learn about remote networks from other routers.

Answer 5

Dynamic Routes

Question 6

Identifies how the route was learned. “O” in the figure indicates that the source of the entry was the OSPF dynamic routing protocol.

Answer 6

Route source

Question 7

Identifies the address of the remote network. The router knows how to reach 172.16.1.0/24 network.

Answer 7

Destination network

Question 8

Identifies the trustworthiness of the route source. Lower values indicate preferred route source. OSPF has a default administrative distance value of 110.

Answer 8

Administrative distance

Question 9

Identifies the value assigned to reach the remote network. Lower values indicate preferred routes. This OSPF route has a metric of 2 for the destination network 172.16.1.0/24.

Answer 9

Metric

Question 10

Identifies the IPv4 address of the next router to forward the packet to. The IPv4 address of the next-hop is 192.168.10.2.

Answer 10

Next-hop

Question 11

Identifies how much time has passed since the route was learned. The information in the example entry was learned 3 minutes and 23 seconds ago.

Answer 11

Route timestamp

Question 12

Identifies the exit interface to use to forward a packet toward the final destination. The packets destined to the 172.16.1.0/24 network will be forwarded out of the GigabitEthernet 0/1 interface.

Answer 12

Outgoing interface

Question 13

Static routes are entries that you manually enter directly into the configuration of the router. Static routes are not automatically updated and must be manually reconfigured if the network topology changes.

Answer 13

Static Routes

Question 14

A default route is an optional entry, which is used by the router if a packet does not match any other, a more specific route in the routing table. A default route can be dynamically learned or statically configured.

Answer 14

Default Routes