While Apache is for the most part a drop-in replacement for NCSA's httpd, there are a couple gotcha's to watch out for. These are mostly due to the fact that the parser for config and access control files was rewritten from scratch, so certain liberties the earlier servers took may not be available here. ... If you follow the NCSA guidelines for setting up access restrictions based on client domain, you may well have added entries for, AuthType, AuthName, AuthUserFile or AuthGroupFile . ...