Hello,
If I understand correctly, on Cisco routers you can configure NAT with PAT using a single public IP address in two ways:
1) Define a pool of just one IP address. Then overload the pool with the following command:
#ip nat inside source list 1 pool poolname overload
2) Do not use pools but just overload the interface with a public IP, like:
#ip nat inside source list 1 interface serial 0 overload
Am I correct ? I ask because in the additional chapter on NAT (ftp://ftp.sybex.com/4391/4391CCNA_NAT.pdf) Todd Lammle doesn't mention case 2) at all and I wonder if there is a technical reason to prefer option 1) vs option 2).
Also, in the event a question like this pops up in the CCNA certification sim, would both answers be considered correct ?
Finally, one last question: Does the network mask in the pool declaration need to be precise or not ? The same Lammle changes each time in his own chapter like this:
ip nat pool poolname 198.18.131.65 198.18.131.70 255.255.255.0
and
ip nat pool poolname 198.18.131.65 198.18.131.70 255.255.255.248
If it's the same, the once again how area those two going to be evaluated by the sim software ? is it smart enough to contemplate such cases ?
Thank you.