What's the command to find the name of a computer given its IP address?

I always forget what this command is, but I know it exists in Windows and I assume it exists on the *nix command-line.

15 Answers 15


The commands dig and host should be what you're looking for ;)

On *nix systems, you can use this command:

dig -x [address]

Alternatively, you can add +short at the end of the dig command to output only the DNS result.

There's also nslookup on both *nix and Windows systems for reverse DNS requests.

  • 4
    The same syntax also works with the drill utility from ldns, i.e. drill -x
    – Tullo_x86
    Sep 19, 2019 at 1:42

On *nix you can use:

dig -x [address]
  • 25
    This definitely seems to be the easiest way. Add +short at the end to return nothing but the rdns result. dig -x [address] +short
    – ColinM
    Mar 1, 2012 at 3:36
  • 7
    That +short flag is really useful!
    – Neil
    Sep 13, 2012 at 13:59
  • Does this work with IPv6 addresses?
    – Geremia
    Sep 12, 2016 at 3:35
  • @ColinM Good point. I've edited my answer based on this. Thanks! Apr 25, 2017 at 11:14
  • Yes, @Geremia, according to man dig, The addr is an IPv4 address in dotted-decimal notation, or a colon-delimited IPv6 address.
    – Ricardo
    Aug 21, 2018 at 22:18

Try "host"

  • Forward lookup with host:

    $ host google-public-dns-b.google.com.
    google-public-dns-b.google.com has address
    google-public-dns-b.google.com has IPv6 address 2001:4860:4860::8844
  • Reverse lookup with host:

    $ host domain name pointer google-public-dns-b.google.com.

Similar to dig

  • Forward lookup with dig:

    $ dig google-public-dns-b.google.com. +short
  • Reverse lookup with dig:

    $ dig -x +short

BTW: dig is picky about its command line options ordering:

  • dig -x +short works.
  • dig +short -x works.
  • dig -x +short does not work.

Try "rdt"

It takes a little more setup. But if you do this, then you can run this "rdt" PHP script from the command line and it's quite wonderful. It does a few back and forth trips between forward and reverse lookups.

Download from here: https://github.com/grawity/code/blob/master/net/rdt

Example. This is what it looks like when it's working:

$ rdt google-public-dns-b.google.com.
google-public-dns-b.google.com. = 2001:4860:4860::8844,
   2001:4860:4860::8844 = dns.google
      dns.google = 2001:4860:4860::8844, 2001:4860:4860::8888,,
         2001:4860:4860::8888 = dns.google = dns.google = dns.google

On most of the Linux systems that I am aware of you can use:

 nslookup <ip-number EX:>

will work on the command line.

Come to think of it, isn't nslookup available on Windows XP?

  • Yes, indeed. And in previous versions of Windows.
    – kubanczyk
    Jul 1, 2009 at 18:30
  • Works on Mac OS Mojave 10.14.6
    – user674669
    Sep 15, 2021 at 3:55

I'm well aware that dig/host/nslookup are the standard tools for these, but I keep these around for testing the OS's resolution (essentially, to test nsswitch.conf is working correctly):



use Socket;

my @t = gethostbyname($ARGV[0]);
print "\$name     = $t[0]\n"; shift(@t);
print "\$aliases  = $t[0]\n"; shift(@t);
print "\$addrtype = $t[0]\n"; shift(@t);
print "\$length   = $t[0]\n"; shift(@t);

foreach (@t) {
  print "          = ", inet_ntoa($_), "\n";



use Socket;

my @t = gethostbyaddr(inet_aton($ARGV[0]), AF_INET);
print "\$name     = $t[0]\n"; shift(@t);
print "\$aliases  = $t[0]\n"; shift(@t);
print "\$addrtype = $t[0]\n"; shift(@t);
print "\$length   = $t[0]\n"; shift(@t);

foreach (@t) {
  print "          = ", inet_ntoa($_), "\n";


g3 0 /home/jj33/swap > gethostbyname www.google.com
$name     = www.l.google.com
$aliases  = www.google.com
$addrtype = 2
$length   = 4
g3 0 /home/jj33/swap > gethostbyaddr 
$name     = qb-in-f147.google.com
$aliases  = 
$addrtype = 2
$length   = 4
  • 4
    you can do "getent hosts [IP or HOSTNAME]"
    – hayalci
    May 27, 2009 at 9:44
  • Hmmm... I wrote the tools originally just to play with the functions, so no loss there but I certainly wouldn't have pasted them into serverfault if I had known about the getent tool. Thanks for the pointer.
    – jj33
    May 27, 2009 at 14:06
  • 1
    -1: they are limited to IPv4, gethostbyname does not retrieve IPv6 addresses when they exist and gethostbyaddr does not accept IPv6 addresses.
    – bortzmeyer
    Sep 23, 2009 at 7:14
  • These functions are many years obsolete. They were even obsolete when this was written. In perl and most other languages you should be using getaddrinfo and getnameinfo. Feb 3, 2016 at 23:58

This question already has a million answers, but I'm gonna add another one. Here's a little function I wrote for easily doing reverse DNS with dig. Add this to your ~/.bashrc file, reload your shell, and then you can do reverse DNS lookups with revdns

function revdns() {

    # split the IP address into an array of octets
    IFS="." read -r -a octets <<< "$1"

    # add each octet to our $addr string in reverse order
    for octet in "${octets[@]}"; do

    # run a DNS pointer lookup with dig
    # `+short` makes dig's output very terse (un-verbose)
    # `"${@:2}"` passes any extra params from this command to dig
    dig ptr +short $addr "${@:2}"

Reverse DNS lookups are done by checking the pointer (PTR) records. If you wanna do reverse DNS for "", you have to lookup pointer records for "". My function takes in an IP address, reverses the order of the octets (i.e. changes it from to, and then uses dig to execute the PTR lookup I just described.

You can, of course, just use nslookup if you have it, but I prefer this dig-based solution because it uses the OS' DNS servers instead of nslookup-provided ones (if you want, by the way, you can add additional dig flags when you call revdns, and they will get passed to dig)

  • 1
    According to its help dig -x dot-notation is the "shortcut for reverse lookups". I was wondering what the long version would be. Thanks for explaining! :)
    – webwurst
    Jul 11, 2018 at 15:43
  • 2
    from man dig: When the -x is used, there is no need to provide the name, class and type arguments. dig automatically performs a lookup for a name like and sets the query type and class to PTR and IN respectively.
    – Ricardo
    Aug 21, 2018 at 22:15

On Windows I got in to the habit of using:

ping -a <ip address>

as this will also reflect data from your hosts file and WINS and so on.


If you're using nslookup it's this (assuming as the IP in question)

> set type=ptr

EDIT: Remember a reverse lookup only works if there is a PTR record created for the IP, and it's not guaranteed to return the hostname you're looking for. Completely depends on how DNS is configured and maintained in your situation.

  • 6
    nsloookup is no longer maintained and its authors recommend dig. Besides, dig -x is much simpler than inversing the bytes yourself.
    – bortzmeyer
    May 12, 2009 at 13:23
  • 1
    That's good to know, thanks a lot for the input! Old habits die hard ;)
    – squillman
    May 12, 2009 at 13:47



I prefer the command-line dig for Windows (available here: http://members.shaw.ca/nicholas.fong/dig/) to nslookup any day.

If you have to test/administer DNS from a Windows workstation, grab this tool. Then:

C:\dig>dig -x <IP Address>

...also, remember to add c:\dig to your path!


Well, some friendly person just wrote nslookup is the command, and he's right. It works on both Unix and Windows. Not sure why you deleted your answer, but you are correct sir.

  • err, maybe not. May 11, 2009 at 15:57
  • Yeah well, I did post a bit fast, and after a check I wasn't sure at all of my answer, I just put back my post and edit it to add more details ;) May 11, 2009 at 15:58
  • OK, it is, but it isn't I'm accepting that answer. Too bad we can't get that real time Googley AJAX here. May 11, 2009 at 15:59
  • lol yeah well, we can't have everything ;) Have a nice day, I hope I help you ;) May 11, 2009 at 16:05

Here are some command line tools for reverse DNS:

  1. Dig:

dig -x [IP Address]

  1. Nslookup:

nslookup -type=ptr [IP Address]

  1. Host:

host [IP Address]


cant leave comment but to install dig on Debian

 apt-get install dnsutils -y ;
 address_i_haz=`curl -s http://ipv4.icanhazip.com` ; # use you own pls dont spam them in prod ;)

 dig -x $address_i_haz ;

nbtstat -a < ip address >

  • 2
    nbstat isn't a DNS utility but rather WINS/NetBIOS Feb 4, 2016 at 1:12

Her's my take on a more complete DNS reverse lookup. Hope this will come in handy to future viewers of this page.

for ip in {1..254..1}; do dig -x 1.1.1.$ip | grep $ip >> dns.txt; done;

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