Online Expert Day - HPE Data Storage - Live Now
April 24/25 - Online Expert Day - HPE Data Storage - Live Now
Read more
System Administration
cancel
Showing results for 
Search instead for 
Did you mean: 

nslookup resolving dns name in reverse order

Shivkumar
Super Advisor

nslookup resolving dns name in reverse order

Hi,

When i tried to resolve ip i got reverse order ip format similar to below one:
-------------------------------------
$nslookup 192.22.11.123

Non-authoritative answer:
123.11.22.192.in-addr.arpa name = somename.com.

Authoritative answers can be found from:
-------------------------------------

Can someone explain what could be the reason ?

Thanks,
Shiv
6 REPLIES
Johnson Punniyalingam
Honored Contributor

Re: nslookup resolving dns name in reverse order

Hi,

I Could guess, You need to Check with your DNS Server Configuration file reverser.dns

Could be some have mistaken the meaning of reverse.dns file while putting entry on the reverse.dns.file ..... :(



Example :-

DNS (Domain Name System) is responsible for translating Internet names (such as www.yourdomain.com) into IP addresses (such as 192.168.1.10). You can think of it like a telephone book for the Internet. Organizations publish DNS records to tell the rest of the world how to reach them.

The DNS is comprised of zones. A zone is either a domain name or an IP network for which a given server is authoritative. When you register a domain you define one or more nameservers -- these are the nameservers which are advertised to the Internet as having authoritative information for the domain.

DNS supports two types of zones: forward, which converts names to addresses, and reverse, which converts addresses to names


HTH,

Johnson

Problems are common to all, but attitude makes the difference
Hakki Aydin Ucar
Honored Contributor

Re: nslookup resolving dns name in reverse order

I recommend to use dig instead of nslookup due to dig is working more accurately.
Matti_Kurkela
Honored Contributor

Re: nslookup resolving dns name in reverse order

The reverse order IP format in DNS is exactly how the DNS reverse lookups are implemented.

A DNS server always starts from the right side of the name. It picks the right-most component of the name (.com or .arpa) and makes a query about it to the Internet root nameservers. The root nameservers will tell it where to find the .com or .arpa Top Level Domain nameservers.

Then the DNS server makes a second round of queries to the appropriate TLD nameserver(s). To find out where the authoritative nameserver for somename.com is, the server asks from the .com TLD nameserver. For in-addr.arpa, the .arpa TLD nameserver is queried. The process continues like this until the authoritative nameserver for the required domain is found. That can then supply the answer that the client requred.

The nameserver typically caches the results of all these steps, so that some (or all) can steps can be skipped if the same or similar name is queried again.

A hostname has the domain part on the right and the individual hostname on the left.
An IP address has the network part on the left and the host address on the right. To allow DNS servers to use the same logic to resolve both IP addresses and hostnames, one or the other must be reversed. When the DNS was designed, a decision was made to reverse the IP address.

MK
MK
Shivkumar
Super Advisor

Re: nslookup resolving dns name in reverse order

I checked with DNS team and they said DNS configuration is fine.
Matti_Kurkela
Honored Contributor

Re: nslookup resolving dns name in reverse order

Yes, I agree.

See my previous reply for an explanation what is happening and *why*.

MK
MK
Steven Schweda
Honored Contributor

Re: nslookup resolving dns name in reverse order

What did you _wish_ to see from this DNS
inquiry? (You did get an answer.)

> I checked with DNS team and they said DNS
> configuration is fine.

Perhaps you should be arguing with them.