Red Hat LINUX 7.2 Reference Manual page 213

Section 13.3:Configuration Directives in httpd.conf 213
13.3.73 ProxyVia
The ProxyVia command controls whether or not an HTTP Via: header line is sent along with re-
quests or replies which go through the Apache proxy server. The Via: header will show the hostname
if ProxyVia is set to On, the hostname and Apache version for Full, any Via: lines will be passed
along unchanged for Off, and Via: lines will be removed for Block.
13.3.74 Cache Directives
A number of cache directives are commented out in the proxy IfModule tags mentioned above. If
you are using the proxy server functionality and you want to also enable the proxy cache, you should
uncomment the cache directives as described. The default settings for your cache directives should be
appropriate for most configurations.
CacheRoot sets the name of the directory which will contain cached files. The default CacheRoot
is /var/cache/httpd.
CacheSize sets how much space the cache can use, in KB. The default CacheSize is 5 KB.
CacheGcInterval sets a number of hours. After that number of hours, files in the cache will be
deleted if the cache is using more space than allowed by CacheSize. The default for CacheGcIn-
terval is four hours.
Cached HTML documents will be retained (without a reload from the originating Web server) in the
cache for a maximum number of hours set by CacheMaxExpire. The default is 24 hours.
The CacheLastModifiedFactor affects the creation of an expiry (expiration) date for a docu-
ment which did not come from its originating server with its own expiry set. The default CacheLast-
ModifiedFactor is set to 0.1, meaning that the expiry date for such documents equals one-tenth
of the amount of time since the document was last modified.
CacheDefaultExpire is the expiry time in hours for a document that was received using a pro-
tocol that does not support expiry times. The default is set to one hour.
Any document that is retrieved from a host and/or domain that matches one set in NoCache will
not be cached. If you know of hosts or domains from which you do not want to cache documents,
uncomment NoCache and set their domains or hostnames here.
13.3.75 NameVirtualHost
You will need to use the NameVirtualHost directive for the IP address (and port number if neces-
sary) of any name-based virtual hosts you are setting up. The name-based virtual hosts configuration
is used when you want to set up different virtual hosts for different domains, but you do not have (or
do not want to use) different IP addresses for all of the different domain names for which your Web
server serves documents.