I have a question about how DNS works.

Assumptions:

I have my own DNS and HTTP servers
On July 1st I register my domain with the registrar and tell the registrar about my own name servers
On July 2nd, Bob successfully goes to my website
On July 3rd, all of the registrar's servers crash and are down for a full week
On July 4th, Sue tries to go to my website


So on July 4th will Sue be able to go to my website?

Does the DNS system rely on the the registrar's servers being up, even when I'm hosting my own DNS servers for my domain?

The answer is, no it doesn't.
The nameserver records you register with your registrar are so called glue records, and they are stored in the registry.. (.com etc).

After you have registered the nameservers it's all up to for example the .com registry, verisign, to host the DNS for the glue records, which again forwards the client to your nameservers where the DNS entries are stored.

Thanks coax.

So my registrar would tell the .com registry that the nameserver for 'example.com' was 'ns1.example.com' at ip address '1.2.3.4'.?

A related question...

What if the registrar goes out of business? Does the registrar have to send daily confirmations of all of this information to the .com registry, or is it set in stone at the registry unless the registrar actively changes it?

When you make a request to register a nameserver, the registrar sends it to the registry yea.

As for the other question, I'm not sure about this, but I think glue records are deleted if the domain is deleted and only then. You can edit glue records to new IP's but you can't delete them (afaik) and they stay that way until the domain is deleted.

When you make a request to register a nameserver, the registrar sends it to the registry yea.

As for the other question, I'm not sure about this, but I think glue records are deleted if the domain is deleted and only then. You can edit glue records to new IP's but you can't delete them (afaik) and they stay that way until the domain is deleted.

Actually you can delete glue records or update the IP.

Glue records are kept at the registry and should get the IP address even the name servers are down at the hosting provider or registrar.

Thanks coax.

So my registrar would tell the .com registry that the nameserver for 'example.com' was 'ns1.example.com' at ip address '1.2.3.4'.?

A related question...

What if the registrar goes out of business? Does the registrar have to send daily confirmations of all of this information to the .com registry, or is it set in stone at the registry unless the registrar actively changes it?

When a registrar goes out of business its major major news. ICANN gets involved and transfers the domain to another registrar. ICANN got a lot of flack when registerfly went down. Since then there has been only one registrar that has gone out of business. It was estdomains and the domains were smoothly transfered to directi.

Its more likely that a reseller of domains goes out of business. In that case you can still contact the original registrar and they'll help you manage your domain.

I imagine a domain is basically a row in some database at the registry . So no daily confirmations are needed.

Basically registrars now have to data escrow all the registrant information (all the whois contact information).

SO should a registrar go pop, ICANN can swiftly move in, get the escrowed info from IronMountain to a new registrar and hey presto.

Before a new nameserver can be used a glue records are needed to be created at registry as the glue records can provide the information on nameserver, Ip address and your domain registrar.