If you register a domain with Cloudflare or Route 53, and that service goes down, do your records stay active in the DNS servers? What if the DNS servers go down, I know a lot of people use 8.8.8.8, so if Google’s server goes down, then DNS fails?
What are the potential point of failures for having your own domain?
If the DNS server for your Domain goes down the records should still be saved in all the other DNS servers around the world. They will stay the same as they were before you domain’s DNS server wen’t down. While your DNS server is down you won’t be able to change where the Domain points. While your registration server is down you will not be able to transfer or sell your domain.
Correct, but not the whole story.
If your registrar goes down, and you have your authoritative DNS anywhere else, then literally nothing happens. They just register the domain for you and give you an interface to pass your ‘glue’ records up to the TLD root servers.
If those glue records point to on-site DNS, or anything that is not your registrar’s DNS servers, then your registrar being down is inconsequential other than that you would not be able to update your glue records, or renew your domain.
A separate question of “what happens if my authoritative servers go down”, is answered above.
The two are not one in the same, though they can be.
You should actually be able to transfer and sell - that’s handled at the tld.
Also, there’s a lifetime to that cache, so if it’s down long enough it’ll become unreachable.
I’ve never really understood the whole TTL thing. Will the domain essentially point to nothing if the TTL runs out while the DNS server is down or will it default to older record?
The record will expire and, in this scenario, effectively become non-existent.
Once upon a time TTLs we’re rather long so temporary outages were less impactive. These days TTLs of less than a minute are common to accommodate redundancy. It doesn’t do want good to have redundant systems if DNS keep pointing at the downed system during an outage.