Sometimes it's handy to have local DNS entries, for example when you're working on a copy of a site on your local machine - perhaps via a VM, vagrant, lxc or docker. A simple way of doing this is to add entries to your hosts file e.g.:
# local site
127.0.0.1 dev.mcdruid.co.uk
It can be a bit of pain though having to set one - or sometimes more - of these up for every new site you work on.