Troubleshooting DNS

If you're having trouble connecting your domain with your website on PythonAnywhere, make sure you have been through our Custom Domains help page. If after that you are still experiencing problems, we've prepared a set of solutions for the most common ones and some background information to help you understand how DNS works.

yourdomain.com is not www.yourdomain.com

This is the cause of about 80% of problems with DNS setup :-)

Technically speaking those two addresses are completely different things -- you could have one website on one, and a completely different one on the other. You should set up your website on www.yourdomain.com and then set up yourdomain.com to redirect to www.yourdomain.com as a separate step.

The name of your website on the "Web" page inside PythonAnywhere needs to be an exact match for the address that people use to visit it, so in all but the most unusual cases it should include the www. So if right now you just have yourdomain.com there instead of www.yourdomain.com, then use the "pencil" icon next to the name to edit it, add the missing www., and your site may start working right away!

For more details about yourdomain.com vs www.yourdomain.com, check out our separate help page about "naked" domains.

"We were unable to find a CNAME for your domain" -- but the site works!

If you see "We were unable to find a CNAME for your domain." message but your website loads normally and appears to be running the code you have configured on PythonAnywhere, it usually mean that your name server provider (usually it happens for Cloudflare using CNAME Flattening) sets redirection in a way that makes us unable to identify a CNAME. It's fine.

But if you're not seeing your website when you visit it, read on...

How to check if your CNAME is properly set up

dig is a tool that can be used to talk to the DNS system to get information about a domain name. We have it installed on PythonAnywhere, so you can run it from a Bash console.

Here is a sample run for a correctly-configured domain, and its output. We'll explain specific parts of it later.

$ dig www.yourdomain.com

; <<>> DiG 9.10.3-P4-Ubuntu <<>> www.yourdomain.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38590
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.yourdomain.com.        IN      A

;; ANSWER SECTION:
www.yourdomain.com. 60 IN   CNAME   webapp-12345.pythonanywhere.com.
webapp-12345.pythonanywhere.com. 60    IN      A       35.173.69.207

;; Query time: 25 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Jun 13 16:46:46 UTC 2019
;; MSG SIZE  rcvd: 113

The most important part of this is the piece labeled "ANSWER SECTION". This shows how the DNS system is handling your domain.

Since www.yourdomain.com is a correctly configured CNAME, it points to webapp-12345.pythonanywhere.com (the first line of the section). The second line shows what IP address that ultimately resolves to.

Another important part of the "ANSWER SECTION" is the number before the IN in the first line. It is the TTL (or Time-to-Live) of the DNS record. Every DNS record has a TTL and that determines how long a machine will cache a result for in seconds. In the example above it would take at least 1 minute for a change to become visible. A TTL of 3600 would take at least an hour, and so on. So if the number there is high, and you've only waited a few minutes for the DNS changes to take effect, you may need to wait longer.

If there is no "ANSWER SECTION", it means that the website address does not exist in the DNS system -- generally that means that you haven't set up the CNAME correctly. The most common cause of this is that the "name" of the CNAME record is wrong. Some registrars require that you enter www.yourdomain.com for the "name" of the CNAME; other registrars only want www. If you enter www.yourdomain.com into the settings for a registrar that only wants www, then they will interpret it as a CNAME record for www.yourdomain.com.yourdomain.com, which obviously won't work. You can check if this has happened by running dig www.yourdomain.com.yourdomain.com -- if that comes back with a correct CNAME setup like the one above, then edit your CNAME record on your registrar's site, so that the name is just www.

If there is an "ANSWER SECTION", you might find that instead of having a CNAME it has something like this:

www.yourdomain.com. 275 IN  A   1.2.3.4

-- the important bit being that it says "A" where the previous example had "CNAME", followed by some numbers instead of webapp-12345.pythonanywhere.com. If this happens, it's because there's an A record rather than a CNAME set up for your domain. Check your DNS setup on your registrar's page -- a common cause of this kind of thing is if you have set up the CNAME correctly for www.yourdomain.com, but your registrar had previously set up an A record for the same address -- the A record overrides the CNAME. Be careful before changing anything here -- if you have an A record that is not for www.yourdomain.com, it's probably OK. But if there is one for that host name, then you should delete it, wait for the change to propagate, and see if that fixes it.

How DNS works

We have also a a seperate help page that describes a little about how DNS works. It's a great place to start if you're confused and don't understand what's really going on with your custom domain.

Still having trouble?

If after puzzling through dig output and trying various things, you still can't get it to work, then you can contact us -- please attach a screenshot of how you've set up the DNS configuration on your domain registrar's site, as that will help us to tell you what needs to be changed.