Propagating a DNS change … Slowly

Propagating a DNS change … Slowly

4 months ago

I’ve bought a couple of .com domains recently from Namecheap, essentially as ‘placeholders’ in some sense, and such that I would be hosting them purely as single-page static sites on AWS. Dead cheap, I must say, they were around $45 each for five years. And, to be honest, the ten or so static sites I host on AWS that make use of S3, Route 53, CloudFront, and Lambda only cost around $5 a month from Amazon. So, basically free, and adding a couple more domains isn’t going to make any difference.

Anyway, yesterday I set about creating the site for one of those domains. A bit of HTML, some CSS, no JavaScript this time. Looked good locally on my laptop, so uploaded to S3 and then created the hosted zone in Route 53. Then the fun thing: over to Namecheap to change the DNS for the domain. AWS give you four name servers to use, so after I’d entered those into the Custom DNS section of the domain page on Namecheap, I went to load the domain in Firefox.

And the default Namecheap holding page came up.

No sweat, just give the DNS changes time to propagate across the internet. A couple of minutes, maybe five? Still came up with the default Namecheap holding page.

Hmmm. Time to flush my local DNS store: Namecheap page.

Clear browsing history from Firefox for the day: Namecheap page.

WTF? Let’s try accessing the domain in Chrome. Comes up with my AWS-hosted page immediately. Edge? My page. Back to Firefox: Namecheap page. What’s up with Firefox, I wondered.

I booted up another laptop. Firefox: no; Chrome: yes; Edge: yes. Really: what the F is Firefox doing?

Well, as far as I can gather, Firefox uses HTTPS to connect to a more secure DNS server to discover how to route a request to a domain. And what I found was that it was taking some time for the name server changes I’d made to propagate to that DNS server. In fact, I went for a walk with the dog, and only by the time I’d got back the changes had propagated to that ‘Firefox’ DNS server and Firefox would now display the correct AWS-hosted page.

You learn something new every day.

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