How to Setup Caching NameServer on CentOS/RHEL 6/5

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Definition at Wikipedia:

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Caching name servers, also called DNS caches, store DNS query results for a period of time determined in the configuration (time-to-live) of each domain-name record. DNS caches improve the efficiency of the DNS by reducing DNS traffic across the Internet, and by reducing load on authoritative name-servers, particularly root name-servers. Because they can answer questions more quickly, they also increase the performance of end-user applications that use the DNS. Read more

This article will help you to setup caching nameserver on your CentOS/RHEL 6 system.

Step 1: Install BIND Packages

Install bind packages using below command. In CentOS/RHEL 6 chaching-nameserver package has been included with bind package.

# yum install bind bind-chroot

Step 2: Create Configuration File

Copy bind configuration file from bind sample files using below command. Change the path of files as per version you have installed.

# cd /var/named/chroot/etc
# cp /usr/share/doc/bind-9.9.2/sample/etc/named.conf  .
# cp /usr/share/doc/bind-9.9.2/sample/etc/named.rfc1912.zones  .

Step 3: Update Configuration File

Edit bind configuration file in your favorite editor and make necessary changes as per below settings or use below configuration.

# /var/named/chroot/etc/named.conf

// /var/named/chroot/etc/named.conf
options {
        listen-on port 53 { 127.0.0.1; any; };
        listen-on-v6 port 53 { ::1; };
        directory       "/var/named";
        dump-file       "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
        allow-query     { localhost; any; };
        allow-query-cache    { localhost; any; };
        recursion yes;

        dnssec-enable yes;
        dnssec-validation yes;
        dnssec-lookaside auto;

        /* Path to ISC DLV key */
        bindkeys-file "/etc/named.iscdlv.key";

        managed-keys-directory "/var/named/dynamic";
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

include "/etc/named.rfc1912.zones";

Now update required permissions on configuration files using below command.

# chown root:named named.conf named.rfc1912.zones

Step 4: Check Configuration File

We recommend to check DNS configuration file before restarting service.

# named-checkconf named.conf

Step 5: Restart Bind Service

Now installation of bind service has been completed. Lets start bind (named) service using following command.

# service named restart

Enable auto start bind service on system boot.

# chkconfig named on

Step 6: Finally Test Caching Only DNS

Send query to your dns server directly using below command.

Syntax: nslookup <domainname> <caching dns server name/ip>

# nslookup yahoo.com 192.168.1.90

[Sample Output:]

Server:         192.168.1.91
Address:        192.168.1.91#53

Non-authoritative answer:
Name:   yahoo.com
Address: 98.138.253.109
Name:   yahoo.com
Address: 98.139.183.24
Name:   yahoo.com
Address: 206.190.36.45

Congratulation’s! You have successfully configured caching nameserver on your linux system. Read out next articles Configure DNS Server on CentOS/RHE 6 and Setup Master Slave DNS Server on CentOS/RHEL 6.

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7 Comments

  1. khalilamar on

    Hello again

    from the /var/log/messages
    I can read the following line: Oct 29 03:06:36 ns named[960]: loading configuration from ‘/etc/named.conf’
    Which means, the /var/named/chroot/etc/named.conf has no relationship with /etc/named.conf

    When I compare both files, I see some differences.
    [root@ns etc]# diff -y /etc/named.conf /var/named/chroot/etc/named.conf
    // <
    // named.conf <
    // <
    // Provided by Red Hat bind package to configure the ISC BIND <
    // server as a caching only nameserver (as a localhost DNS re <
    // <
    // See /usr/share/doc/bind*/sample/ for example named configu <
    // <
    dnssec-lookaside auto;

    /* Path to ISC DLV key */ | /* Path to ISC DLV key */
    bindkeys-file “/etc/named.iscdlv.key”; | bindkeys-file “/etc/named.iscdlv.key”;

    managed-keys-directory “/var/named/dynamic”; | managed-keys-directory “/var/named/dynamic”;
    }; };

    logging { logging {
    channel default_debug { channel default_debug {
    file “data/named.run”; file “data/named.run”;
    severity dynamic; severity dynamic;
    }; };
    }; };

    zone “.” IN { <
    type hint; <
    file "named.ca"; <
    }; <
    <
    include "/etc/named.rfc1912.zones"; include "/etc/named.rfc1912.zones";
    include "/etc/named.root.key"; <

    [root@ns etc]#

    And…
    from http://www.howtoforge.com/perfect-server-centos-5.6-x86_64-ispconfig-3-p5
    Can you explain why did this guy do the following ?

    chmod 755 /var/named/
    chmod 775 /var/named/chroot/
    chmod 775 /var/named/chroot/var/
    chmod 775 /var/named/chroot/var/named/
    chmod 775 /var/named/chroot/var/run/
    chmod 777 /var/named/chroot/var/run/named/
    cd /var/named/chroot/var/named/
    ln -s ../../ chroot
    touch /var/named/chroot/var/named/named.local
    cp /usr/share/doc/bind-9.3.6/sample/var/named/named.root /var/named/chroot/var/named/named.root
    touch /var/named/chroot/etc/named.conf.local
    vi /var/named/chroot/etc/named.conf

    //
    // named.conf
    //
    // Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
    // server as a caching only nameserver (as a localhost DNS resolver only).
    //
    // See /usr/share/doc/bind*/sample/ for example named configuration files.
    //
    options {
    listen-on port 53 { any; };
    listen-on-v6 port 53 { any; };
    directory "/var/named/chroot/var/named";
    dump-file "/var/named/chroot/var/named/data/cache_dump.db";
    statistics-file "/var/named/chroot/var/named/data/named_stats.txt";
    memstatistics-file "/var/named/chroot/var/named/data/named_mem_stats.txt";
    allow-query { any; };
    recursion no;
    allow-recursion { none; };
    };
    logging {
    channel default_debug {
    file "data/named.run";
    severity dynamic;
    };
    };
    zone "." IN {
    type hint;
    file "named.root";
    };
    include "/var/named/chroot/var/named/named.local";

    Reply
  2. khalilamar on

    You need to add: yum install bind-utils
    for those that are following your instructions right after a clean install from CentOS minimal.
    Thanks

    Reply
  3. Bill Carlson on

    Isn’t there any other option or package to use for a dns cache?

    For me and many, BIND is specifically a very poor piece of software and wish to avoid.

    Debian has several variants, I don’t understand why Redhat Enterprise would not have a good robust alternative.

    Reply
  5. Burak on

    Hi,

    Using yum install and update named I have bind.x86_64 version 30:9.3.6-20.P1.el5_8.6 installed on Centos 5.5 64bit.
    It is working and running. However, I suspect that it does not do caching.
    So I tried to use some lines from your configuration.
    When I run, named displayed following errors:
    unknown option ‘allow-query’
    unknown option ‘allow-query-cache’
    unknown option ‘recursion’
    unknown option ‘dnssec-enable’
    unknown option ‘dnssec-validation’
    unknown option ‘dnssec-lookaside’

    What could be the reason, is centos 5 too old?

    Reply
  6. Adrian on

    Hello! first of all thanks for taking the time to read my query …

    Know where cahe record is saved?
    is to find the sites visited by my office terminals and generate blocking rules for certain domains.

    thank you very much!

    Adrian!

    pd: sorry for my bad English

    Reply

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