Edit: I believe this will only work if the router is your DNS server, is in involved as your DNS resolve. The benefit of adding this to the router's hosts file (assuming the router is your dns) is that the FQDN can be resolved by any host. Otherwise, you will need to add it to a client's hosts file.
As an alternative, if you only have a few client systems, you can also add a similar entry on the clients host file (name and location vary depending on the operating system).