2.3.176 UseCanonicalName

Description

UseCanonicalName specifies how to generate the canonical name of the web server. The canonical name of the web server is set in the URL that references the local server and in the environment variables SERVER_NAME and SERVER_PORT. Note that IPv6 addresses are supported for all of the following: On, Off, and dns.

Syntax

UseCanonicalName {On|Off|dns}

Specifiable values

On

Creates the canonical name of the web server from the value specified in the ServerName directive, and then sets the name into the URL that references the local server and into the environment variables. If an IP address is specified in the VirtualHost directive, specify ServerName within the VirtualHost block. If ServerName is not specified within the block, the host name will be obtained from the IP address.

Off

Creates the canonical name of the web server from the host name and the port number given from the client by the Host header, and then sets the name into the URL that references the local server and into the environment variables. However, if the Host header cannot give this information, the canonical name of the web server is created from the value of the ServerName directive and the port number used in the actual connection.

dns

This option is for old clients that do not have Host headers. If you specify this option, the canonical name of the web server is created by reverse resolution of the IP address given by the client and the port number that is actually being used in the connection, and then the name is set into the URL that references the local server and into the environment variables.

Default value

If the definition item is omitted:

Off

Locations where it can be written

httpsd.conf, <VirtualHost>, and <Directory>