Dynamic NAT netmask question

mikeybinec

I'm pretty confident on all the objectives for the CCENT exam but one thing that confuses me still is the subnet mask when defining Dynamic NAT

For example, ip nat pool MIKEY 209.165.200.1 209.165.200.12 netmask 255.255.555.0

In the above example, if my public pool is only 12 IP addresses, why is the netmask a /24?

It seems to me it should be a /28, but every example I have seen in learning and labs always calls out a /24.

Can somebody enlighten me?

Thanks

shyguyIT

You use a /24 because the first three octets are part of the network address and the last octet is the host portion.

N.N.N.H

With a /24 you can have 254 hosts of which you are using 12 in your NAT pool.

xnx

A /28 should be suitable here, you've added up from the wrong octet

mikeybinec

Yeah, I noticed I put a /20 instead of the correct /28. But the gist is a /28 would be fine

Thanks