Ping domain name vs nslookup IP
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From: SL Da on 22 Sep 2009 21:31 1. When I ping 'bayregatta.com' I see 209.160.33.87 2. When I try 'nslookup 209.160.33.87', I get 'non-existent domain'. I am a bit confused. Can someone explain ? Thanks.
From: Wanna-Be Sys Admin on 22 Sep 2009 22:01 SL Da wrote: > 1. When I ping 'bayregatta.com' I see 209.160.33.87 > > 2. When I try 'nslookup 209.160.33.87', I get 'non-existent domain'. > > I am a bit confused. Can someone explain ? > > Thanks. You probably get a failure (can't find) "87.33.160.209.in-addr.arpa", which means you don't have reverse DNS set up. If you are authoritative, you can add a PTR record to the DNS. Otherwise ask your provider to do it, if you need rDNS for any reason. You can also run "host ip.address.here" for a shorter response, too. You can also add the domain and IP locally to your hosts file. -- Not really a wanna-be, but I don't know everything.
From: David Schwartz on 22 Sep 2009 22:15 On Sep 22, 6:31 pm, SL Da <sb5...(a)yahoo.com> wrote: > 1. When I ping 'bayregatta.com' I see 209.160.33.87 > > 2. When I try 'nslookup 209.160.33.87', I get 'non-existent domain'. > > I am a bit confused. Can someone explain ? Why are you confused? It would help if you explained what you found confusing about this. Forward and reverse namings are completely independent. The two questions follow completely different paths, and if they provide corresponding answers, it's only because someone carefully set them up that way. DS
From: SL Da on 22 Sep 2009 23:23 I don't have much knowledge in this area. When I create a domain on a web server, there is no problem. I suppose all entries are done automaticaly by the ISP's software. But then suddenly there are problems (someone else's domain). First the domain cannot be reached, now the reverse DNS does not work. I think someone has tempered the DNS record, or removed the domain account form the server (I guess). > Why are you confused? It would help if you explained what you found > confusing about this. Forward and reverse namings are completely > independent. The two questions follow completely different paths, and > if they provide corresponding answers, it's only because someone > carefully set them up that way. > > DS
From: David Schwartz on 23 Sep 2009 00:00
On Sep 22, 8:23 pm, SL Da <sb5...(a)yahoo.com> wrote: > I don't have much knowledge in this area. > When I create a domain on a web server, there is no problem. I suppose > all entries are done automaticaly by the ISP's software. Some hosting companies may do this if you host the domain locally. But they are doing two logically independent things based on a single trigger. > But then suddenly there are problems (someone else's domain). First > the domain cannot be reached, now the reverse DNS does not work. I > think someone has tempered the DNS record, or removed the domain > account form the server (I guess). There's no way to tell without troubleshooting. But that reverse DNS doesn't work doesn't tell you anything, since it's not required. DNS is not bidirectional. An entry that maps www.example.com to 1.2.3.4 is part of the zone for "example.com" and managed by whoever or whatever managed "example.com". An entry that maps 1.2.3.4 to www.example.com is part of the zone for 3.2.1.in-addr.arpa and managed by whoever or whatever manages that block of IP addresses. There is, in general, no way to find what names map to a particular IP address or all the IP addresses that reverse to a particular name. Each entry goes only one way. DS |