[DarkDeviL]

You can't.

Steam games has for years only been using IP address for their services. You can however add a server to your favorite list and similar things with a DNS name, but it won't remember the DNS name, but only the IP address.

CS:GO, CS:S, TF2 and perhaps some other Source engine games allows you to use a Game Sever Login Token (GSLT) to give your server an unique token that will make uses follow your server based on it's token rather than it's IP address.

This one works such as if I have refreshed my player list on February 20, at 15:00 CET, then my Steam client will remember your token <-> IP combination until February 21 , at 15:00 CET - after which it will then refresh the IP addresses again, based on the token. As such, it may take your users up to 24 hours to propagate the change of your IP address.

That functionality however won't work properly if you are using one of those "automatic token generator"-services and/or somehow else are switching tokens every now and then.