How to allow connections to domains without a dot?
Sometimes your browser can connect to URLS containing non fully qualified domain name (also called domain name without any dot in it). Something like http://forms/authenticate.php?blabla. The forms part here is non fully qualified, contains no dots and generally DNS servers need some special hint on how to resolve such domain names.
It is possible to provide this hint to Squid in UI/Squid/Settings/DNS section of the Admin UI, by filling the Append Domain Name text field. Note that the domain name to append MUST begin with a dot.
See the following article for more information http://www.squid-cache.org/Doc/config/append_domain/ .