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by SLuijk 5281 days ago
Yes I quite agree with you, for established domains. It's interesting that only 3% of resolvers are parent-centric.

I was referring more to when registering a domain. To prevent the IPS resolver caching a non existent NS record for negative TTL.
2 comments
colmmacc 5281 days ago
The article suggests that both Google Public DNS and nominum are parent centric, which might be a significant portion of the 3% (or larger at this point).

These days with the number of resolvers that have fall-back catch-all records designed to redirect you to a search / suggest feature, I think that you also need to worry about positive TTLs.

You're right that if a domain is pristine, and has never been queried, that in all likelihood, you'll be able to have it resolvable within minutes, not hours, but this still seems like a relatively uncommon case.

In practice, people do query for their domain as its propagating, and do buy meaningful names that are likely to have some low-level background rate of queries, and there's not much to stop the legion of bots that are watching for whois updates either.

I guess I take the most issue with your headline. DNS taking 48+ hours to propagate is not a myth.

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Terretta 5281 days ago
Problem is, both your link headline here and the premise headlined on your blog are flat wrong, and are going to give sysadmins everywhere headaches if clients come across your article and think they've learned something.

The RFC snippet quoted in this comments thread is the right approach: keep a long TTL in normal practice, shorten it at least double the TTL in advance of a change (e.g., if 2 day TTL, shorten it 4 days before changes), dropping it down to 3600 or 300 depending on your tastes, and bring it back up after the change is stabilized.

In the case of registering a brand new, never existed before, domain, avoiding cache poisoning can help.

But DNS taking up to (TTL x number of layers of cache) is not a myth. We routinely see 5 - 7 days (globally) on 1 and 2 day TTLs, and 2 - 3 days (globally) on 5 minute TTLs (thanks to ISPs with 1 day min TTLs).

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