mod_dns 1.3 review

mod_dns is a Apache module that allows busy servers to resolve hostnames in realtime. The module uses a shared memory cache to sto

License: GPL (GNU General Public License) File size: 9K Developer: Fredrik Sjoholm

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mod_dns is a Apache module that allows busy servers to resolve hostnames in realtime.

The module uses a shared memory cache to store recently resolved hostnames. By default the cache uses 200k of shared ram, and will cache up to 1024 ip/host pairs.

mod_dns dramatically improves resolver performance, making it possible to resolve hostnames in real-time even for busy webservers.

Installation:

Define the APACHE_HOME environment variable (needed to find $APACHE_HOME/bin/apxs) then type make: (or do it all in one line..) % APACHE_HOME=/z/httpd/ make

Configure:

# load module and turn off Apache core gethostbyaddr() function LoadModule dns_module libexec/mod_dns.so
HostnameLookups Off

#< Location ... >
DnsLookups On
DnsTimeout_ms 5500
DnsResendTimer_ms 1900
#< /Location >

# built-in statistics page
< Location /mod_dns/stats >
SetHandler dns-stats-handler
< /Location >

5500 ms is the default timeout, UDP packets will be resent to the DNS server every 1900 ms (DnsResendTimer_ms). These directives can be configured per-directory, if for some reason its more important to resolve a host-name in one place than another.
Notice that once the cache has a bad entry in it, it will not be resolved again until it expires.

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Requirements:
Apache 1.3
EAPI & mm (Apache shared memory API)