RT 4.0.1 Error

Getting this in the error log. Some of my users use an IP to access RT, others use the fqdn. Is it possible to have an FQDN and IP set in the $WebDomain?

[Tue Jul 12 20:12:48 2011] [warn]: The actual HTTP_HOST ( does NOT match the configured WebDomain (rt.ahlta.saic.com). Perhaps you should Set($WebDomain, ‘’); in RT_SiteConfig.pm, otherwise your internal links may be broken. (/opt/rt/sbin/…/lib/RT/Interface/Web.pm:1087)