3.4.1. ServerName

ServerName hostname 
Server config, virtual host

3.4.2. UseCanonicalName

This directive controls how Apache forms URLs that refer to itself, for example, when redirecting a request for http://www.domain.com/some/directory to the correct http://www.domain.com/some/directory/ (note the trailing "/" ). If UseCanonical-Name is on (the default), then the hostname and port used in the redirect will be those set by ServerName and Port. If it is off, then the name and port used will be the ones in the original request.

One instance where this directive may be useful is when users are in the same domain as the web server (for example, on an intranet). In this case, they may use the "short" name for the server (www, for example), instead of the fully qualified domain name (www.domain.com, say). If a user types a URL such as http://www/somedir (without the trailing slash), then, with UseCanonicalName switched on, the user will be directed to http://www.domain.com/somedir/, whereas with UseCanonicalName switched off, he or she will be redirected to http://www/somedir/. An obvious case in which this is useful is when user authentication is switched on: reusing the server name that the user typed means they won't be asked to reauthenticate when the server name appears to the browser to have changed. More obscure cases relate to name/address translation caused by some firewalling techniques.

3.4.3. ServerAdmin

ServerAdmin email_address
Server config, virtual host

3.4.4. ServerSignature

This directive allows you to let the client know which server in a chain of proxies actually did the business. ServerSignature on generates a footer to server-generated documents that includes the server version number and the ServerName of the virtual host. ServerSignature email additionally creates a mailto: reference to the relevant ServerAdmin address.

3.4.5. ServerTokens

This directive controls the information about itself that the server returns:

min(imal)

Server returns name and version number, for example, Apache v1.3

OS

Server sends operating system as well, for example, Apache v1.3 (Unix)

full

Server sends the previously listed information plus information about compiled modules, for example, Apache v1.3 (Unix) PHP/3.0 MyMod/1.2

3.4.6. ServerAlias

ServerAlias gives a list of alternate names matching the current virtual host. If a request uses HTTP 1.1, it arrives with Host: server in the header and can match ServerName, ServerAlias, or the VirtualHost name.

3.4.7. ServerPath

It has to be said that this directive often doesn't work very well because it requires a great deal of discipline in writing consistent internal HTML links, which must all be written as relative links to make them work with two different URLs. However, if you have to cope with HTTP/1.0 browsers that don't send Host headers accessing virtual sites, you don't have much choice.

For instance, suppose you have site1.somewhere.com and site2.somewhere.com mapped to the same IP address (let's say 192.168.123.2), and you set up the httpd.conf file like this:

<VirtualHost 192.168.123.2>
ServerName site1.somewhere.com
DocumentRoot /usr/www/site1
ServerPath /site1
</VirtualHost>

<VirtualHost 192.168.123.2>
ServerName site2.somewhere.com
DocumentRoot /usr/www/site2
ServerPath /site2
</VirtualHost>

Then an HTTP/1.1 browser can access the two sites with URLs http://site1. somewhere.com / and http://site2.somewhere.com /. Recall that HTTP/1.0 can only distinguish between sites with different IP addresses, so both of those URLs look the same to an HTTP/1.0 browser. However, with the above setup, such browsers can access http://site1.somewhere.com/site1 and http://site1.somewhere.com/site2 to see the two different sites (yes, we did mean site1.somewhere.com in the latter; it could have been site2.somewhere.com in either, because they are the same as far as an HTTP/1.0 browser is concerned).

3.4.8. ServerRoot

ServerRoot specifies where the subdirectories conf and logs can be found. If you start Apache with the -f (file) option, you need to include the ServerRoot directive. On the other hand, if you use the -d (directory) option, as we do, this directive is not needed.

3.4.9. PidFile

A useful piece of information about an executing process is its PID number. This is available under both Unix and Win32 in the PidFile, and this directive allows you to change its location. By default, it is in ... /logs/httpd.pid. However, only Unix allows you to do anything easily with it; namely, to kill the process.

3.4.10. ScoreBoardFile

The ScoreBoardFile directive is required on some architectures in order to place a file that the server will use to communicate between its children and the parent. The easiest way to find out if your architecture requires a scoreboard file is to run Apache and see if it creates the file named by the directive. If your architecture requires it, then you must ensure that this file is not used at the same time by more than one invocation of Apache.

If you have to use a ScoreBoardFile, then you may see improved speed by placing it on a RAM disk. But be aware that placing important files on a RAM disk involves a certain amount of risk.

Apache 1.2 and above: Linux 1.x and SVR4 users might be able to add -DHAVE_SHMGET -DUSE_SHMGET_SCOREBOARD to the EXTRA_CFLAGS in your Config file. This might work with some 1.x installations, but not with all of them. (Prior to 1.3b4, HAVE_SHMGET would have sufficed.)

3.4.11. CoreDumpDirectory

Specifies a directory where Apache tries to dump core. The default is the ServerRoot directory, but this is normally not writable by Apache's user. This directive is useful only in Unix, since Win32 does not dump a core after a crash.

3.4.12. SendBufferSize

Increases the send buffer in TCP beyond the default set by the operating system. This directive improves performance under certain circumstances, but we suggest you don't use it unless you thoroughly understand network technicalities.

3.4.13. LockFile

When Apache is compiled with USE_FCNTL_SERIALIZED_ACCEPT or USE_FLOCK_SERIALIZED_ACCEPT, it will not start until it writes a lock file to the local disk. If the logs directory is NFS mounted, this will not be possible. It is not a good idea to put this file in a directory that is writable by everyone, since a false file will prevent Apache from starting. This mechanism is necessary because some operating systems don't like multiple processes sitting in accept() on a single socket (which is where Apache sits while waiting). Therefore, these calls need to be serialized. One way is to use a lock file, but you can't use one on an NFS-mounted directory.

3.4.14. KeepAlive

3.4.15. KeepAliveTimeout

KeepAliveTimeout seconds
Default seconds: 15
Server config

3.4.16. TimeOut

TimeOut seconds
Default seconds: 1200
Server config

3.4.17. HostNameLookups

The new double keyword supports the double-reverse DNS test. An IP address passes this test if the forward map of the reverse map includes the original IP. Regardless of the setting here, mod_access access lists using DNS names require all the names to pass the double-reverse test.

3.4.18. Include

Include filename 
Server config