Ask HN: Why does news.Y Combinator.com use a DNS TTL of 1s?

#1

Post by 500ktc » Sat, Nov 09, 2024, 11:54 PM UTC

This result in every page load making a DNS request.

This is a questionable technical choice, especially considering HN's status as the SaaS mecca. So it begs the question: Why?

If the goal is to be able to rapidly switch to cloudflare when under attack then surely a TTL of 600 or 60 would be sufficient whilst being more respectful of your visitors?

Re: Ask HN: Why does news.Y Combinator.com use a DNS TTL of 1s?

#2

Post by toomuchtodo » Sun, Nov 10, 2024, 12:33 AM UTC

For fast failover to the backup server. The lack of DNS caching is immaterial, lookups are cheap, network and CPU is cheap (wrt serving DNS).

It’s not a questionable technical choice (imho) based on the use case. Simplicity is the ultimate sophistication.

Re: Ask HN: Why does news.Y Combinator.com use a DNS TTL of 1s?

#3

Post by jsharkey » Sun, Nov 10, 2024, 12:58 AM UTC

NextDNS has a "Cache Boost" option that, when enabled, clamps answers to a minimum TTL to mitigate things like this. I've noticed that some Samsung IoT domains also have aggressively low TTL.

Re: Ask HN: Why does news.Y Combinator.com use a DNS TTL of 1s?

#4

Post by [deleted] » Sun, Nov 10, 2024, 2:21 AM UTC

[deleted]

Re: Ask HN: Why does news.Y Combinator.com use a DNS TTL of 1s?

#5

Post by ironmagma » Sun, Nov 10, 2024, 3:30 AM UTC

I'm legitimately curious what environment you're in where you notice/care about the extra DNS lookup?