Useful DNS tools for setup, migration & propagation
The Domain Name System is what binds (excuse the pun) the internet together. By configuring DNS NS (NameServer) and the various other DNS records we can ensure others on the internet know how to connect to us and more.
But DNS can be tricky and these tools can help you check whether everything really is set up okay, or whether there's a problem somewhere.
The following are external websites, not in any way affiliated with Krystal, but they are our go-to tools for checking what's going on with DNS.
This site gives a general check on DNS and mail server (MX records) health.
Simply enter your domain name (only enter your apex/naked domain name, don't include the www. or any other hostname part) and click the Report button.
Ideally you'll see mostly green ticks. Blue entries are informational. Yellow rows are warnings - usually fine, but worth reading.
If you see any Red then something may require fixing.
Often during site migrations from one host to another, or if you switch from shared hosting to a VPS or dedicated server you'll almost certainly need to change the nameservers for your domain.
When you change a DNS record, the change is live on your own nameservers immediately. What takes time is everyone else finding out.
DNS servers all over the world keep a copy of the answers they have already been given, so that they do not have to ask again for every visitor. How long they keep each answer is set by that record's TTL (Time To Live). A resolver that looked up your site five minutes before you made the change will keep serving the old answer until the TTL runs out. That waiting period is what people mean by "propagation", and it is why a change can appear instantly for you and not for someone else.
How long it takes is therefore set by the TTL, not by a fixed rule - anything from a few minutes to 48 hours. See the tip at the end for how to shorten it before you make changes.
The What's my DNS tool allows you to pop your domain in and it'll look-up and show your DNS NS records from servers around the world.
Type your website's name in the box and then select the type of DNS record you'd like to check (e.g. NS = nameservers, A = Address record, MX = Mail eXchanger) and click the Search button.
You'll see the list on the left populate with details held by servers around the world - from which you can glean whether propagation is working and how quickly it is progressing.
Bear in mind that it's unlikely these test servers around the world have queried your domain before - so they will be doing so for the first time - which may influence the result. Whereas more local servers, used by you or visitors to your site may still have a validly cached version of your domain's original DNS details.
One thing these tools cannot tell you: if they show the new value from servers all over the world and your own browser still loads the old site, the stale copy is on your own machine rather than out on the internet. See how to flush your computer's DNS cache.
Changing nameservers is different. That change happens at the domain registry, not in your zone, and the registry sets its own TTL on it which you cannot edit. For .uk domains it is currently 172800 seconds - two days. So lowering the TTLs in your own zone does not speed up a nameserver change, and you should plan for up to 48 hours.
