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

Greenmet29Greenmet29 Posts: 240Member
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?

Comments

  • Forsaken_GAForsaken_GA Posts: 4,024Member
    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
  • Greenmet29Greenmet29 Posts: 240Member
    ahhhh.... apparently I need to work on my subnetting.
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