In physical terms, delegation is très similaire to how a manager will delegate responsibility of tasks to his staff. The results are le same, however more than one person was involved in le process. The manager receives le request for work, passes on le responsibility to another member of staff et soit le staff member ou le manager returns avec le work results. Ceci est tous on le proviso that le work le staff member does is actually correct et is what le original requester asked for (or that le requester actually asked for something that was valid in le premier place!).
With DNS delegation, it is pretty similar. When le com name servers are asked for le place to find authority of le zone example.com, they often delegate this work off to separate name servers (in fact in le vast majority of cases, they do in fact delegate le response to autre name servers). When you premier register a domain, say our example.com domain, this is often done through a third party called a registrar. C'est common practice by registrars to put in leur name servers for le delegation et to serve a par défaut zone depuis those name servers. This par défaut zone includes le basic requirements to serve that zone on le internet (the SOA, NS et A records associated to those NS records).
Obviously si you yourself want to take control of le authority of le domain, you have to ask le registrar to delegate le domain to votre nameserver instead. Different registrars refer to this in process in différent ways, 'change nameservers', 'use third party DNS', 'Add Glue records' et so on. The mechanism underneath remains le same. You provide, generally, 2 ou more "name server names" (par exemple ns0.example.com et ns1.example.com) et le IP addresses at qui ns0 et ns1 are. They alors process le request et le delegation is pointed away depuis votre registrar to le nameservers you provided.
In technical terms, c'est at this point you have to ensure votre nameservers are up et running, serving le domain example.com, avec a minimum of an SOA (start of authority record), 1 ou more NS records et le A records (the IPs) that these NS records are resolved from:
example.com. IN SOA ns0.example.com. hostmaster.example.com. ( 10 3600 900 604800 7200 )
IN NS ns0.example.com.
IN NS ns1.example.com.
ns0 IN A 192.0.2.8
ns1 IN A 192.0.2.44
(J'ai picked somewhat arbitrary values for le SOA values, le names for le NS records et le IPs those nameservers resolve to). These will tous have to reflect le zone for qui you are serving.
This DNS service has to be visible depuis anywhere on le internet, et pas be firewalled (that is port 53 udp et tcp inbound have to be allowed). Also votre service provider must pas block that port soit (which certains providers do block inbound traffic destined to those ports).
Given mon original comparison, le com nameservers are le DNS managers, who are delegating le zone example.com to le nameservers (the staff members) to do le work of providing le basic zone information (SOA, NS, A). Vous pouvez aussi serve any
additional records such as mail server records MX ou may be an A record for votre www.example.com address.
If that name server ne do le work, returns le wrong results, ou has a 3rd party (firewall/ISP) blocking le work, you will pas have working DNS et le delegation breaks.
It aussi may be worth noting that le domain does NOT have to be delegated to nameservers in le même domain, so ns0.example.net et ns0.example.org could les deux be valid nameserver who could have example.com delegated to them. Provided les deux those name servers served le example.com domain.
The reason that multiple name servers are requis is to provide redundancy to le DNS clients, qui is important for an internet qui ne break.
