Tag Name log_fqdn
Usage log_fqdn on|off

Description
This tag can be set to ON, if you wish to log fully qualified domain names in the access.log.

Default log_fqdn off

Example
log_fqdn on

Caution
To do this, Squid does a DNS lookup of all IP’s connecting to it. This can (in some situations) increase latency, which makes your cache seem slower for interactive browsing.