RHEL7: Configure a caching-only name server.

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Note: This is an RHCE 7 exam objective.

Presentation of Caching-only Name Server

A cache-only name server keeps a cache of all the results of the previous requests to the root DNS servers.

Configuration Procedure

Install the bind package:

# yum install -y bind

Edit the /etc/named.conf file and change the listen-on option from 127.0.0.1 to any:

listen-on port 53 { any; };

In the same file, change the allow-query option from localhost to any:

allow-query { any; };

In the same file, disable the dnssec-validation option:

dnssec-validation no;

Check the configuration file:

# named-checkconf

Add a new service to the firewall:

# firewall-cmd --permanent --add-service=dns
success

Reload the firewall configuration:

# firewall-cmd --reload
success

Activate the DNS service:

# systemctl enable named

Start the DNS service:

# systemctl start named

Time to Test

Check the configuration:

# nslookup cnn.com 127.0.0.1
# dig @127.0.0.1 cnn.com

Additional Resources

You can also read this nice article from Zytrax.com about the different DNS Configuration Types.
If you want to go any further, check the master DNS server tutorial.

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9 Comments on "RHEL7: Configure a caching-only name server."

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Shikaz
Member
Shikaz

In one of the tutorials I have seen they are installing unbound instead of bind, do you thing from the RHCE perspective it will matter to install bind or unbound?

Jaz
Member
Jaz

What if I put my interface ip address in listen-on port directive and add my network ip in allow-query directive during the exam even if not asked in the question?
Because ‘any’ means no restriction.

dan
Member
dan

why set dnssec-validation to no?

power
Member
power

Hi Guys,
I haven’t seen any DNS question on RHCE mock test. Do you think that might be included in the exam ?

Thank you

Lisenet
Member

It might be as it’s a part of RHCE exam objectives.

I’ve put a sample RHCE example exam here: https://www.lisenet.com/2016/rhce-sample-exam-for-rhel-7/ feel free to give it a try.

mairj23
Member
mairj23

Hi everyone, when I configure a cache only dns server it doesn’t resolve any domain, but it works correctly when I add forwarders any ideas? If I ping a domain from shell it works…
Thanks in advance

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