In addition to the operating-system-vendor-supplied Apache versions, a number of companies offer servers based on Apache.
IBM: The latest IBM HTTP server is based on Apache 2.0 with additional modules added (such as encryption). The IBM HTTP server is also part of the Websphere Application Server suite. You can find more about this server at http://www-4.ibm.com/software/webservers/httpservers.
Covalent: Covalent offers Enterprise Ready Server (ERS), based on Apache 2.0. ERS includes support for SSL, FTP, and LDAP, and includes a graphical management interface component. You can find more about ERS at http://www.covalent.net.
Red Hat: Although at the time this book was written, Red Hat did not offer a 2.0-based Web server, it is likely to do so in the future as part of its secure and commerce servers. More information about Red Hat's Apache products can be found at http://www.redhat.com/software/apache/index.html.