Minimizing downtime when moving a website

Situation: you move a website to another server but the dns changes propagates slowly and this causes the effect that some visitors sees the new site and some others the old.

One way to cope with this is by setting a reverse proxy. The purpose of the proxy is to direct all HTTP traffic to another server. In apache, this can be accomplished with these directives:

# A.B.C.D is the server IP that gets the traffic
ProxyPreserveHost On
ProxyPass / http://A.B.C.D/
ProxyPassReverse / http://A.B.C.D/

Don't forget to install and enable the mod_proxy mod.