How does a router choose the route to send a packet?

Greenmet29

The routes ip addresses in question are:

172.16.1.1
172.16.1.2
172.16.2.2
172.16.4.3

show ip route rip:

R 172.16.1.1/32 .....
R 172.16.1.0/24 .....
R 172.16.0.0/22 .....
R 172.16.0.0/16 .....

The book says that the router would choose the route with the longest prefix, but that 172.16.4.3 would go out 172.16.0.0/16.

Wouldn't 172.16.0.0/22 have the longer prefix?

Forsaken_GA

Greenmet29 wrote: »

The routes ip addresses in question are:

172.16.1.1
172.16.1.2
172.16.2.2
172.16.4.3

show ip route rip:

R 172.16.1.1/32 .....
R 172.16.1.0/24 .....
R 172.16.0.0/22 .....
R 172.16.0.0/16 .....

The book says that the router would choose the route with the longest prefix, but that 172.16.4.3 would go out 172.16.0.0/16.

Wouldn't 172.16.0.0/22 have the longer prefix?

No. 172.16.0.0/22 is equivalent to 172.16.0.0 to 172.16.3.255, so 4.3 doesn't fit.

You've gotta remember that 0 is a discrete, valid number, it does not indicate null

Greenmet29

ahhhh.... apparently I need to work on my subnetting.