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

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,

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Comments

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