[toast0]

> Your domain registrar is the gatekeeper for glue NS records, so if your primary DNS host[1] ever had a sustained down period, it's still relatively simple and fast to update your nameservers as needed.

It's simple, but not exactly fast. .com and .net glue records have a TTL of 2 days, so expect significant delay. Different tlds have different times though, .org is only 1 hour, and I'm not looking up anything else ;)

[wahern]

Good point, I forgot about TTLs in the recursive chain.

How common is it for recursive resolvers to cache glue records? Is it more common for in-bailiwick NS domains?

(This issue exists regardless of setup, so I hope the OP and others aren't dissuaded from exploring their options.)

[toast0]

I'd expect all caching recursive resolvers to cache glue records as well as the requested records. It's part of the deal; if they didn't, the root servers would have an insane load. (After all, you need to get glue records for .com, etc, too)

Of course, there's probably exceptions, and cache size is limited. I can say that some resolvers seem to cache glue records for a long time, more than the published TTL; when I switched NS records for a popular domain, we continued to get requests on the old domain for more than 4 weeks (at which point we needed to end the previous service).