Know Where Your DHCP Server Is...

I came across a 'wireless down' situation the other day where the customer said that they could not connect to wireless.  So when I showed up, I found that you could actually connect to wireless, it was just that I could not get an IP address from the DHCP server.  So, it just so happened that I did not know where the DHCP server was on this network.  Since this place was not too big, it happened that all the PCs and Phones had a static IP address.  So where was DHCP coming from for the wireless?  After some searching, I found that the DHCP server was actually the Cisco ASA, and that the wireless AP was plugged into the core switch, in a different VLAN (with no ip helper address) than the ASA.  So, easy enough once I knew the network.  I just moved the AP over to the ASA 5505 and all was good.  But, I think this is an important piece in that you should always know where the DHCP server is for a network, so that troubleshooting these kinds of problems becomes a lot easier.