What is a DNS Check?

The DNS service is often one of the most overlooked services when analysing website problems. Developers often focus on the webservices, and they forget about the DNS servers, that play a crucial role while troubleshooting website & email errors.

What is a DNS Check? Do I need one for my website?

A dns check, also known as dns report, is just a anlaysys of your DNS servers. This is done by using automated tools like dnslog.com

DNS checkers will analyze each and everyone of the aspect of your DNS servers, including A, CNAME, MX and TXT records. This tools can give you great suggestions on how to improve your DNS & mail health.

A DNS Report tool run a complete DNS test for the specified domains, and then analize all your records looking for performance, configuration and security errors.

Alternative ways to run a DNS Test

Tools like the one we mentioned are often the best way to test your DNS servers, however, if you have deep knowledge of the dns system and how it works, you can also use our beloved dig command or nslookup to analyze your dns & mail configuration.

For example, if we need to know the confiiguration of our main A record, we would end up using this command.

dig A nixcp.com

This should be the output:

[webtech@localhost ~]$ dig A nixcp.com

; <<>> DiG 9.10.4-P6-RedHat-9.10.4-4.P6.fc25 <<>> A nixcp.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27496
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 7

; EDNS: version: 0, flags:; udp: 512
;nixcp.com.			IN	A

nixcp.com.		841	IN	A

nixcp.com.		85441	IN	NS	ns3.dnsmadeeasy.com.
nixcp.com.		85441	IN	NS	ns4.dnsmadeeasy.com.
nixcp.com.		85441	IN	NS	ns2.dnsmadeeasy.com.
nixcp.com.		85441	IN	NS	ns0.dnsmadeeasy.com.

ns0.dnsmadeeasy.com.	82373	IN	A
ns2.dnsmadeeasy.com.	86126	IN	A
ns3.dnsmadeeasy.com.	83493	IN	A
ns3.dnsmadeeasy.com.	84921	IN	AAAA	2600:1801:3::1
ns4.dnsmadeeasy.com.	86055	IN	A
ns4.dnsmadeeasy.com.	79930	IN	AAAA	2600:1802:4::1

;; Query time: 6 msec
;; WHEN: Fri Apr 21 08:18:49 -03 2017
;; MSG SIZE  rcvd: 263

[webtech@localhost ~]$ 

From there you can analyze the records, of course you will have to know all (or the most important ones) the DNS rules and specifications by the IETF organization.

About the Author: Esteban Borges

Experienced Sr. Linux SysAdmin and Web Technologist, passionate about building tools, automating processes, fixing server issues, troubleshooting, securing and optimizing high traffic websites.