ICND2 - VLSM, which IP's will be rejected?

Node Man

Hi Everyone,
Ok, I'm missing something somewhere. I don't see it mentioned in the Odom book, but its in the practice questions. What are the conditions that an ip address gets rejected?

Thanks,

Vask3n

Pretty sure it would get rejected if the address overlaps with an address given to another vlan/subnet. That is why when doing VLSM the goal is to start with the biggest subnets first, it helps with finding overlap.

NetworkVeteran

Common cases where an IP is rejected--

• An IP address that isn't a valid host address given the associated mask and subnet-zero settings.
• An IP address range that overlaps with another IP address range on the same router

Vask3n

NetworkVeteran wrote: »

Common cases where an IP is rejected--

• An IP address that isn't a valid host address given the associated mask and subnet-zero settings.

Just to illustrate this I tried it in GNS3:

R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int loop 1
R1(config-if)#ip add 10.0.0.0 255.0.0.0
Bad mask /8 for address 10.0.0.0