CODEWITHSUNDEEP
dns
eselk
eselk

Reputation: 6894

How do other DNS servers find mine?

I'm trying to learn as much as possible about DNS, and so far I've read most of:

http://www.zytrax.com/books/dns/ch8/soa.html

and all of:

http://computer.howstuffworks.com/dns.htm

I understand that SOA and NS records contain info about the authoritative name server for a domain, but as these are just DNS records, how does the rest of the world even know where to get them?

I assume it starts at the top-level-domain (.COM .NET .ORG, etc) servers. So they must contain a SOA record for my domain? If so, how does that get there? I imagine only registrars like GoDaddy and Network Solutions are able to update those? If they contain a SOA record, why does my DNS server (that I host), need one also? I think there must be something, maybe in the domain registration records (outside of DNS?), that I'm missing.

I think I've got a pretty good understanding of most parts of the DNS system, after reading lots of articles.. but I haven't found any that answer this part, in a way that I understand it.

For example, GoDaddy and Network Solutions both let me change different options (in their web UI) to "host my own DNS server". If these options remove them from the process, so DNS servers never need to query them again, and instead query my server directly (this is what I want, no dependency on GoDaddy/NS)... when I make these changes, what (at the DNS level or otherwise) is GoDaddy/NS doing? Are they asking the top-level-domain servers to update some DNS records for my domain?

Upvotes: 2

Views: 472

Answers (2)

Leo
Leo

Reputation: 2326

So they must contain a SOA record for my domain?

Multiple answers possible, depending on the scenario:

delegated 2nd level:

No; the start of authority of your domain is usually at your level, so the SOA for you.cf is (only) in your nameservers. Same as the SOA for .cf is only in the nameservers of .cf, and not in the root-servers. In case your nameservers are within the same domain (i.e. ns1.you.cf in case of you.cf) then glue records are needed. This means that registry that's operating the TLD's nameservers will insert a A and/or AAAA record with the IP of ns1.you.cf in the TLD zone. Normally you (the registrant) set this in the interface of your registrar.

undelegated 3th level:

No; if your domain was sub.you.cf - but sub.you.cf wasn't delegated (no NS records exist for sub.you.cf) then the SOA is probably at you.cf. Unless...

undelegated 2nd level:

Yes; if you register a domain without having it delegated (no NS records exist for you.cf) then the SOA is at the .cf nameservers. Although most registries run delegation-only zones, some don't. Example: when you use url-fwd'ing in .cf. The SOA then is at the cf level.

Upvotes: 1

dtorgo
dtorgo

Reputation: 2116

Short answer is yes. Godaddy will take care of updating your the TLDs for you. Your other assumptions are also correct except for one small detail...

DNS starts with the "root" domain and then goes to the TLDs (top level domains).

www.somedomain.com. actually brakes down like this:

. The root name servers com - The TLD name servers somedomain - Your NS servers www - The host portion of the dns name.

Setting up your own DNS server is a great way to understand DNS better. Good luck!

Upvotes: 1

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