Lab — Quick NAT & DHCP refresher

Mon, 29 Jun 2026 00:00:00 +0000

I thought to myself, it had been a couple of weeks since setting up NAT and DHCP in a lab. Therefore, I decided to do a quick refresher to ensure I still remembered the process and commands. As it turns out, I still remembered them well, and this lab only took about 10 minutes to get going.

What’s Configured

Firstly, I configured the IP link between Router 0 and Router 1 (Router 1 is simulating the internet). Then I added a loopback interface to Router 1 (internet/ISP router) with the IP address of 1.1.1.1 and set the default route to go back to Router 0. A note on setting the default route: this is a trap that caught me a few times in the past, and it will probably catch me again. When simulating an ISP this way, we need to set the default route to point back to the edge router of the network; otherwise, return traffic from the ISP router doesn’t know how to get back to the LAN.

NAT on Andy Als

Lab — Quick NAT & DHCP refresher

What’s Configured