CCNA Day 11 - Routing Fundamentals

Routing Table

Where do routers store routes to all of their known destinations?

Routing Table

When routers receive packets, they look in the […] to find the best route to forward that packet

A static route is manually configured route.

What is a static route?

A dynamic route is a route that is added to the routing table by a protocol (ie. OSPF) that allows routers to communicate with each other and share routing information.

What is a dynamic route?

The next hop is the next router in the path to the destination.

What is ‘next hop’?

show ip route

Show the routing table:

R1#[…]

Connected

What does code C in the routing table mean?

Local

What does code L in the routing table mean?

A connected route and a local route.

Which two routes are automatically added to the routing table when you configure an IP address on an interface?

A local route is a route to the actual IP address configured on the interface.

What is a local route?

A connected route is a route to the network the interface is connected to.

What is a connected route?

The router will select the most specific matching route

If a packet’s destination IP is matched by multiple routes, which route will the router select?

It is the matching route with the longest prefix length.

How is the most specific matching route determined?

Drop the packet

What will a router do if none of its routes match a packet’s destination IP address?

/32

What prefix length do Local Routes use?

The prefix length configured on the interface.

What prefix length do connected routes use?

Default gateway

Where does a PC send packets in order to send packets outside of its local network?

0.0.0.0/0

A default route is a route to [network]/[netmask]

A default route is the least specific route possible.

What is a default route?

No, it only needs a route to the destination network

Does a router need a route to every network in the path to a packets destination?

ip route [ip-address] [netmask] [next-hop]

Configure a static route, specifying the next-hop IP:

R1(config)#[…]

ip route [ip-address] [netmask] [exit-interface]

Configure a static route, specifying the exit-interface:
R1(config)#[…]

ip route [ip-address] [netmask] [exit-interface] [next-hop]

Configure a static route, specifying the exit-interface and next-hop IP:

R1(config)#[…]

S

What code in the routing table indicates a static route?

ip route 0.0.0.0 0.0.0.0 [next-hop]

Configure a default route, specifying the next-hop IP:

R1(config)#[…]

Directly-Connected

What does a static route appear as in the routing table if you specify only the exit interface?

Default route

What route is often used to direct traffic to the internet?

It means a default route has not been configured.

In the routing table, what does “Gateway of last resort is not set’ mean?

*

What code in the routing table indicates a candidate default route?