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I want the results of

nslookup MyIP

to give my fully qualified domain name instead of the name u123123123.online-servers.com which is setup by default by my host provider, how do I do that?

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2  
Contact your provider. There's nothing you can do yourself. –  Dennis Mar 5 '13 at 1:16
    
@Dennis I have root access to my server, and I'm using DNS manager for my domain in Godaddy, I'm not using NameServers, do I still need to contact them ? –  Shehabic Mar 5 '13 at 1:32
    
@Shehabic yes, you need to contact them. Root access and DNS manager are irrelevant for reverse-DNS. Only person who owns the IP address range (= your ISP) can do it. –  Alex Mar 5 '13 at 8:07

3 Answers 3

up vote 4 down vote accepted

The person that needs to update the record is the person who controls the in-addr.arpa. DNS zone related to your IP address.

THe ISP that provided your IP address has control of this zone.

These in-addr.arpa zones are something that get delegated to an ISP when they receive an IP allocation from their regional registry.

If you only care about having things look right for yourself, you can setup a in-arpa.addr zone for your own IP/network on your own server. People will frequently do this for the RFC1918 address space.

See also: http://en.wikipedia.org/wiki/Reverse_DNS_lookup

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As Dennis mentioned, Your provider will maintain the reverse DNS records. Some providers will change the records for you upon your request, but some will not.

Contact your provider and ask the question, there's nothing else you can do.

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I'd say most, as in 99% of providers won't do that, especially those that use dynamic IPs. –  Mxx Mar 5 '13 at 1:27
    
I have root access to my server, and I'm using DNS manager for my domain in Godaddy, I'm not using NameServers, do I still need to contact them ? –  Shehabic Mar 5 '13 at 1:31

I want the results of

nslookup MyIP to give my fully qualified domain name instead of the name u123123123.online-servers.com which is setup by default by my host provider, how do I do that?

So.. the issue here is whether you want just your hosts to see the names you set up or whether you want everybody else's hosts to see them as well.

You can set up, locally, authoritative reverse zones for your in-addr.arpa domains and your nameserver will answer clients that query it with the answers you want it to give.

The problem, and the reason other people are telling you you need to get your ISP to make the change, is that while you can configure your own clients to ask your nameserver for the PTR records for your reverse zones, you cannot get other people's clients to ask your nameserver without having authority for those zones delegated to you.

Step back for a moment and think about how a DNS client gets an answer to a DNS query. The client has very little a priori knowledge about the Domain Name System. Typically the DNS library on the client knows only enough to ask a local nameserver to handle the query for it (the very limited resolver that runs on the client is called a stub resolver.) The stub resolver asks its query of the nameserver it has been configured to ask, and sets a flag in the DNS header (the "recursion desired" or "RD" flag) saying "if you do not know the answer, please find it for me."

The recursing resolver that is in charge of satisfying the query usually doesn't have much initial knowledge of the DNS tree, either. Typically is is primed only with a list of servers that answer queries for the topmost (root) level of the DNS. When it gets a query it checks its local authoritative data (if it has any) and data that it has built up in its cache to see whether it already knows the answer, and presuming it does not, it starts working its way down from the root.

Delegation

Let's say that you want to ask the DNS a query (of any type) for w.x.y.z. Who is responsible for answering that, and how does your resolver know how to find them? Your client is typically going to ask your local resolver to resolve the query for "w.x.y.z." Let's assume that your resolver doesn't have anything in its cache already and has to go through the whole thing.. It's going to start at the top level of the DNS (that trailing ".") and say "hey, root server, tell me what I want to know about "w.x.y.z."

And the root server will say "hell, man, I don't know the answer to that. go talk to that dude over there.. I've got an NS record (a delegation) saying he knows all about .z." This is called a referral. So your resolver goes back, not quite to square one, and says "hey, resolver that knows all about ".z.", tell me what I want to know about "w.x.y.z.", and the resolver that know all about .z. says "hell, man, I don't know the answer to that. go talk to so and so, I've got an NS record saying she knows all about ".y.z."

And so a client works its way down the chain of delegation from the root, following the NS records which delegate responsibility for answering records for the delegated zones. This works the same way for all record types, whether you're asking about A records, CNAMES, MX, or what have you. Since it works for all record types it obviously also works for PTRs, too.

Reverse Zones

The zones that are part of the .in-addr.arpa. hierarchy use the same NS records for delegation that all other zones do, but delegations in that hierarchy are assigned to the entities that own (by assignment) a block of IP address space. At some point in the past your ISP went to a Regional Internet Registry and requested a block of IP addresses, which were assigned to it as its own address space. As part of that assignment they received a delegation in the Domain Name System for the part of in-addr.arpa that corresponds to their assignment.

The point here is that anybody following a chain of delegation from the root of the DNS is going to get to your ISP, and not to you, unless you can convince your ISP to further delegate responsibility for just your IP address(es) to you. This is why the respondents above are telling you you have to deal with your ISP: if you want your reverse IP mappings to be visible to anybody except for clients who are configured to ask your nameservers for an answer first, you must either (a) get the ISP to make the changes you want, or (b) delegate authority to you. Otherwise nobody else will ever see the answers you have configured your server to give.

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