When you change a DNS record or a domain's nameservers, the change takes effect immediately on the server that answers for the domain. The rest of the internet learns about it gradually: each network has remembered the old answer and keeps using it until it expires. That expiry time is called TTL (time to live), and the wait from start to finish is called propagation.
What you'll achieve
- understand why some people see the new website and others the old one;
- check what the DNS server answers, without waiting for caches;
- plan a move so the downtime is minutes, not days.
If the website is coming from another host, we can do the move for free, testing it on the new server before the DNS change: see Free migration.
How long it actually takes
| What you change | How long it usually takes |
|---|---|
| a record in the zone hosted with us (A, CNAME, MX, TXT) | as long as its TTL: by default with us 1400 seconds, about 23 minutes |
| the domain's nameservers, at the registrar | a few hours; sometimes up to 48 hours, because the extension's registry has its own, longer TTL |
| a newly registered domain | a few hours until it's visible everywhere |
The steps
A. Check the answer, bypassing caches
- Open https://toolbox.googleapps.com/apps/dig/ (Google Admin Toolbox), enter the domain and choose the type: NS for nameservers, A for the website's address, MX for email, TXT for SPF and verifications.
Or, from Terminal (Mac, Linux), ask our server directly:
dig +short A domeniul-tau.ro @ns1.nbt-host.ro dig +short NS domeniul-tau.roOn Windows, in PowerShell:
nslookup domeniul-tau.ro ns1.nbt-host.ro.- If
ns1.nbt-host.roalready returns the new value, the change was made correctly; the rest is just waiting.
B. Clear the cache on your computer
- Windows, in Command Prompt:
ipconfig /flushdns. - Mac, in Terminal:
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder. - Your browser has a cache too: try a private window, or your phone on mobile data.
C. Plan a website move without downtime
If you're moving the website to another server or changing its IP, you can bring the downtime close to zero:
- A day before, lower the TTL of the records you'll change (
@,www,mail) to 300 seconds. In Enhance, on the record: “⋯” » “Edit”, untick “Use zone default” and enter 300 under “TTL”. Wait at least as long as the old TTL, so every network learns the new TTL. - Prepare the website on the new server and test it before the switch, with the
hostsfile (the steps are in Moving a WordPress site from another host, under “Checking before you change the DNS”). - Change the record. Within 5 minutes, most visitors reach the new server.
- Once everything works, set the TTL back to “Use zone default”.
For a nameserver change, you can't lower the TTL at the extension's registry. The rule there is different: set up the zone on the new nameservers, with all the records, before the change. With our nameservers, the zone is already set up in Enhance from the moment the website is created (see How to point your domain to NBT Host).
D. What to do while propagation runs
- Don't switch back at the first sign that “it doesn't work”: some visitors would be sent back and forth.
- Keep the old server running too for a few days, with its email. Messages that arrive there in the meantime aren't lost; you can move them afterwards (see How to move your old emails from another provider).
- Check in Enhance, under “Domains”: the “DNS status” column shows “DNS ok” once the domain points to us.
If something doesn't work
- It's been 48 hours and the old server still shows. This is no longer propagation. Check the nameservers with Dig (step 1): if they aren't the new ones, the change at the registrar wasn't saved. If they are, check the A record. More steps are in The website won't open or shows the old version.
- Dig shows the new value, but your browser shows the old one. It's your local cache or your network's. Clear it (steps 4–6) or try on mobile data.
- The domain stopped answering entirely after the nameserver change. DNSSEC is still active from the old provider. Turn it off at the registrar (see DNS zone editor: A, CNAME, MX and TXT, the section on DNSSEC).
- Email sometimes reaches the old server, sometimes the new one. That's normal while the MX change propagates. Check both mailboxes until it's done.