How to install Djbdns to optimize qmail mail system send mail speed

The QMail mail system reports the following error when sending mail to a large site with multiple MX: Delivery 55371:deferral:cname_lookup_failed_temporarily._ (#4.4.3)/, On the official website of QMail, we learned that installing DJBDNS can speed up DNS resolution and increase the speed and efficiency of qmail mail delivery, and the following is the detailed process of installing DJBDNS.

1. Install Djbdns, the package can be downloaded in http://cr.yp.to/djbdns/djbdns-1.05.tar.gz.

[Root@mail qmail] #tar-zxvf djbdns-1.05.tar.gz

[Root@mail QMail] #cd djbdns-1.05

Before CentOS make, execute the following command in the djbdns-1.05 directory:

[Root@mail djbdns-1.05]# echo gcc-o2-include/usr/include/errno.h > conf-cc (otherwise it will be an error)

[Root@mail djbdns-1.05]# make

[Root@mail djbdns-1.05]# make setup Check

After the installation is complete, you can see programs such as Dnscache,tinydns in the/usr/local/bin directory.

2. Establish the Djbdns configuration file.

[Root@mail djbdns-1.05]# makedir-p/etc/dnscache

[Root@mail djbdns-1.05]# dnscache-conf Nobody nobody/etc/dnscache 127.0.0.1

[Root@mail djbdns-1.05]# ln-s/etc/dnscache/service

[Root@mail djbdns-1.05]# Svstat/service/dnscache (start service)

3. View the Djbdns service if a 127.0.0.1:53 port appears in the description configuration succeeded.

[Root@mail ~]# netstat-antl |grep LISTEN |grep "53"

TCP 0 0 127.0.0.1:53 0.0.0.0:* LISTEN

4. Modify the DNS configuration file, add nameserver 127.0.0.1 under/etc/resolv.conf, and recommend that you put it in front of the other nameserver, so DNS resolution will be prioritized to find the DNS cache.

5. With the dig command Test www.google.com.cn, the first resolution is through the Internet DNS server for resolution www.google.com.cn, the entire parsing process took 181 milliseconds.

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