So VLSM is really just saying well, I want to find one subnet mask for that network, one subnet mask for that network and then pushing it all together. So now let's move in to our example of VLSM. Take this network environment. We've got three networks, oh, we'll say three user networks of 20 users, 20 users and 60 users. And then we've got three networks of WAN links that we can't forget about that would have like two devices each, right? So here's our scenario and this is how you'll be able to tell if we're getting a VLSM question.