Step-by-step guide: preview your site before you switch DNS

Your new host runs nameservers that know your domain as soon as your account is set up, even while the rest of the internet still points at the old server. That's where we look your site up. You'll usually find them in one of these places:

• the welcome or "new account" email your host sent;
• your hosting control panel, in a panel called something like Server information, Account information or Nameservers.

They look like hostnames, usually in pairs, such as ns1.example.net and ns2.example.net. Either one will do. Moving to us? The form already has our nameserver filled in.

While you're there, note the new server's IP address too, often labelled Shared IP, Server IP or Dedicated IP. It looks like four numbers separated by dots, such as 203.0.113.10, and it's what you'll point your domain at when you switch DNS.

No nameserver? On a VPS or cloud server you may only have an IP address, shown on the server's page in your provider's dashboard (often labelled Public IPv4). That works too: on the form, choose Enter the IP address and type it instead. If your host gave you a server name rather than an IP address, dig +short server1.example.net prints its IP address.

Using Cloudflare or another CDN? Enter your new server's own IP address, not the CDN's.

On the home page, type your domain, such as example.com. Pasting a whole address like https://example.com/ works too. The nameserver field starts with our own nameserver: if you're moving somewhere else, replace it with your new host's, such as ns1.example.net. Then press Create preview.

Know the server's IP address? Choose Enter the IP address and type it instead.

We ask that nameserver for your domain's address. It knows your domain once your new host has set up its DNS zone, usually as soon as the account exists, even though the rest of the internet still points at the old server. If it hasn't, you'll see "We couldn't find this domain on ns1.example.net".

Signed in? You'll also see a Link lasts menu, where you choose how long the link works, from 1 to 30 days.

This takes a few seconds. While it works, you'll see the steps listed in order:

• Checking DNS (shown as dns): we ask the nameserver you gave for your domain's address, or use the IP address you gave, and check that public DNS doesn't already send visitors to that server;
• Contacting your server (shown as probe): we ask the server at that IP address for your homepage, under your domain name, over HTTPS first and then HTTP. Any reply counts, even an error page;
• Creating the link (shown as link): we make your preview link.

Common messages

• "This domain already points to that server, so there is nothing to preview." Public DNS already sends visitors to that IP address, so you can visit the site directly. If you've only just switched DNS, the change may not have reached you yet.
• "We found example.com at 203.0.113.10, but nothing answered on ports 80 or 443." The nameserver gave us an address, but no web server answered there on port 443 (HTTPS) or 80 (HTTP). Check the new server is switched on and accepting web traffic. If that isn't your new server's address, check the nameserver.
• "That domain or IP address didn't work." The domain isn't a valid one, or the server at the IP address you typed didn't answer on port 443 (HTTPS) or 80 (HTTP). Check the domain and IP address for typos.
• "We couldn't find this domain on ns1.example.net." The nameserver doesn't know your domain yet: your new host hasn't set up its DNS zone, or it's the wrong nameserver. Check the domain is spelled correctly, and copy the nameserver from your new host's welcome email or control panel.
• "We couldn't find the nameserver ns1.example.net." The nameserver's name has a typo. Copy it from the welcome email or control panel.
• "That doesn't look like a nameserver." Enter a hostname such as ns1.example.net, or an IP address, with no https:// or slashes.
• "This domain or IP address can't be used for a preview." Private and internal network addresses are blocked. More about rejections.

Your preview link looks like https://3f9a1c7e.sitepreview.org/. The eight characters at the start are unique to your preview. From here you can copy the link to share it, open it, or scan the QR code to open it on your phone.

Links last 3 days. With a free account you choose anything from 1 to 30 days. When a link expires it stops working and is deleted; just create a new one if you need more time. If you're signed in, the preview is also saved to your dashboard.

Open the link and use your site as a visitor would. Every page you open through it comes from your new server, whatever DNS says today.

What to look for

• Every important page loads: the homepage, your key landing pages and the contact page.
• Images, styles and scripts load: nothing broken, missing or unstyled. Files served from other domains, such as a CDN or font service, load from their usual place, not your new server. So do your site's own subdomains, such as cdn.example.com or shop.example.com: only your domain and its www. address are sent to the new server, and anything else loads from wherever DNS points today.
• Forms and search work.
• Logins, if your site has them. Simple logins often work; admin logins and single sign-on may not (why?).
• The pages really come from the new server. A quick way to be sure: upload a small test file to the new server only, such as preview-test.txt, and open it through the preview link.
• Try it on a phone too, and watch for security or mixed-content warnings.

A free account gives you:

• Links that last up to 30 days
• A dashboard of all your previews
• Extend, pause, label and delete the links you create while signed in
• Warnings when a preview's homepage returns an error or its server stops answering

Your dashboard shows each preview you created while signed in, with its link, server IP address, views and expiry.

A warning pill such as ⚠ 404 or ⚠ 500 beside the status means your site's homepage is currently returning an error through the preview, as of the most recent visit (or our check when you created it). ⚠ Unreachable means the server didn't answer at all. Hover over the pill, or tap or tab to it, to see the error and when it was first seen.

Fix it before you switch DNS: once DNS points at the new server, every visitor gets that same error. After fixing it, open the homepage through the preview again and the warning clears.

Where your domain's DNS is managed (usually your domain registrar, your old host or a DNS service), change the A record for your domain, and for www if it has its own, to the new server's IP address, the one you noted in step 1. If there's an AAAA (IPv6) record, update or remove that too.

If your new host will run your DNS as well, you can instead change your domain's nameservers, at your domain registrar, to the new host's: the ones you used for the preview.

• Allow time for the change to spread. It can take from a few minutes to a day or two for everyone to see the new server, depending on the record's TTL. Lowering the TTL a day beforehand makes the switch quicker.
• Sort out SSL. Make sure the new server has a valid certificate for your domain before or straight after switching; many hosts issue a free one automatically once DNS points at them. A working preview doesn't prove the certificate is ready, because previews work even with a self-signed or expired certificate.

If something breaks after switching, change the A record back to the old IP address while you fix it. Once the switch is done, you can delete the preview from your dashboard or just let it expire.