I have a few websites that I need to move to a new server - how would I test that they work before switching DNS? What URL would I navigate to?
The easiest way is to modify your hosts file to hardcode the domain name to the new IP address temporarily. See this guide for OS-specific instructions. Don't forget to remove the entry again after you're done testing.
Alternatively, you could setup a temporary test subdomain for each site on the new server (
test.example.com), set it up as an alias, and use this to test with. If you're using control panel software (like cpanel), sometimes these can automate this process, giving you a temporary URL to test with instead.