Pass data such as username in hostname

Question

I have seen some sites use hostnames as data such as usernames (for example username.example.com) and was wondering how you would be able to achieve this.

Is it good practice to use hostnames like this or are there reasons against it?

Thanks in advance.

Answer 1

It is generally bad practice to treat hostnames this way. Lookups become a bit more complicated and it is always safest to use usernames in the path or query.

Hostnames are designed to be thought of in a global sense. For instance user.example.com/username/profile

It also helps protect the user (a little) because paths can be encoded into the http request where a subdomain request essentially requests user.example.com and that request can be redirected multiple times before returning to the client and dns monitoring is the number one way that people do tracking.

DNS tracking is easy because its already fast, open, and the contents aren't designed to be hidden like https or more recent ipsec techniques.

Answer 2

I've accomplished this by setting up a DNS wildcard with your DNS host (*.example.com) then using PHP to parse out the username in the URL and act accordingly.