Checking Domain TTL Values

Checking Domain TTL Values

4th January 2019 - 5 minutes read time

Part of the process of putting a new site live can be moving DNS entries around. Prior to doing this it's a really good idea to sort out the Time To Live (TTL) of the DNS record so that when you do change DNS entries you aren't waiting around for a day for the DNS to sort itself out. Most DNS registrars will allow you to set your TTL down to a minute or so.

It's also very important to check the status of your DNS records to ensure that they have the correct TTL, usually a day before (and day of) the move.

You can check the TTL value of your A record with the host command. Change the value of the -t (type) flag to aaaa or cname to inspect different types of records.

host -a -t a www.hashbangcode.com

This will produce the following output. The TTL of the domain below is '125'.

Trying "www.hashbangcode.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 42916
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.hashbangcode.com.		IN	A

;; ANSWER SECTION:
www.hashbangcode.com.	125	IN	A	104.31.77.1
www.hashbangcode.com.	125	IN	A	104.31.76.1

Received 70 bytes from 10.0.0.4#53 in 4 ms

It's also possible to check the same result with dig using the command.

dig +nocmd +noall +answer +ttlid www.hashbangcode.com

This produces the following result. The TTL value for the domain is '91'.

www.hashbangcode.com.	91	IN	A	104.31.76.1
www.hashbangcode.com.	91	IN	A	104.31.77.1

If you are worried that the response has been cached up stream (which is how DNS works and why you need to lower the TTL in the first palce) you can directly interrogate the DNS name server for a response. This is done using the whois command.

whois hashbangcode.com

This will tell you a lot about the domain name. The important bit of information is called Name Server. Different TLD providers will produce different whois ouputs, but the information will be in there somewhere.

For my own site the name server entries looked like this.

Name Server: ernest.ns.cloudflare.com
Name Server: lorna.ns.cloudflare.com

With this information in hand you can directly interrogate the DNS server using the following.

dig +nocmd +noall +answer @ernest.ns.cloudflare.com www.hashbangcode.com

This is perhaps the most reliable way to test your domain TTL values as it cuts out any caching of results.

Finally, always remember to check all domains and sub-domains you are migrating. This especially means checking the www and non-www variants of every address you are migrating.

DNS

Add new comment

The content of this field is kept private and will not be shown publicly.
CAPTCHA
17 + 0 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Related Content

Using The Fingerprint Scanner On Pop! OS 22.04

30th April 2023

I work on a couple of ThinkPad laptops (T490 and a P14s) and whilst they have fingerprint scanners I haven't really considered using them. I once attempted to get a fingerprint scanner working in Linux on an old HP laptop and that experience put me off trying again.

Read more

Timing Page Responses With Curl

27th March 2022

Timing web requests is possible in curl using the -w or --write-out flag. This flag takes a number of different options, including several time based options.

Read more

Repointing A Symlink To A Different Location

10th December 2020

In Linux, creating a symlink is a common way of ensuring that the directory structure of a deployment will always be the same. For example you might create a symlink so that the release directory of release123/docroot will instead be just current.

Read more

Grep Context

27th June 2020

Grep is a really powerful tool for finding things in files. I often use it to scan for plugins in the Drupal codebase or to scan through a CSV or log file for data.

For example, to scan for user centric ViewsFilter plugins in the Drupal core directory use this command (assuming you are relative to the core directory).

Read more