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Is there a command to perform just DNS lookups on a domain name? Such as dns unix.stackexchange.com which would return 151.101.1.69 and gbnjk.com would return error: domain not found.

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4 Answers 4

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5

Another DNS query tool, dig, is very verbose by default, but if you use it as dig +short, you get just the answers, one per line:

$ dig +short unix.stackexchange.com
151.101.65.69
151.101.193.69
151.101.129.69
151.101.1.69

$ dig +short www.latimes.com
32975.edgekey.net.
e11929.e12.akamaiedge.net.
2.22.63.16
2.22.63.11

If the requested domain does not exist, it just returns nothing:

$ dig +short gbnjk.com
$
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Yes, there are several.

ISC tools and various flavours of host

The tools that accompany ISC's BIND are host and dig. You can see their operation, including dig's short mode, in other answers here.

The ISC is not the only source of a host tool, however.

  • Knot DNS comes with its own khost tool. On Debian, this is packaged in the knot-host package which also supplies a symbolic link that makes it accessable as host as well.
    % host unix.stackexchange.com.
unix.stackexchange.com. has IPv4 address 151.101.1.69
unix.stackexchange.com. has IPv4 address 151.101.65.69
unix.stackexchange.com. has IPv4 address 151.101.129.69
unix.stackexchange.com. has IPv4 address 151.101.193.69
Host unix.stackexchange.com. has no AAAA record
Host unix.stackexchange.com. has no MX record
%
  • I provide a host tool for use with the djbwares toolset, which I also provide in the form of a djbdns-host Debian package. It is a thin wrapper around the native djbdns query tools. Unlike the Knot and ISC host tools, which as you can see from the aforegiven do multiple transactions in some cases, it always performs just one DNS transaction.
    % host unix.stackexchange.com.
1 unix.stackexchange.com:
104 bytes, 1+4+0+0 records, response, noerror
query: 1 unix.stackexchange.com
answer: unix.stackexchange.com 300 A 151.101.1.69
answer: unix.stackexchange.com 300 A 151.101.65.69
answer: unix.stackexchange.com 300 A 151.101.129.69
answer: unix.stackexchange.com 300 A 151.101.193.69
%
% host gbnjk.com
1 gbnjk.com:
27 bytes, 1+0+0+0 records, response, authoritative, nxdomain
query: 1 gbnjk.com
%

Daniel J. Bernstein tools

The native djbdns query tools are dnsq, dnsqr, dnsqrx, dnsname, dnsnamex, dnsmx, dnsip, dnsipq, dnstxt, and dnstrace. There are many of them because they split into three categories:

As aforementioned, the human-readable tools perform just one DNS transaction, and print the contents of the response from the relevant DNS server (different tools being tailored to specific types of DNS server, content or proxy).

% dnsqr ns stackexchange.com.
2 stackexchange.com:
170 bytes, 1+4+0+0 records, response, noerror
query: 2 stackexchange.com
answer: stackexchange.com 170156 NS ns-1029.awsdns-00.org
answer: stackexchange.com 170156 NS ns-925.awsdns-51.net
answer: stackexchange.com 170156 NS ns-cloud-d1.googledomains.com
answer: stackexchange.com 170156 NS ns-cloud-d2.googledomains.com
% 
% dnsq ns stackexchange.com. ns-925.awsdns-51.net.                                                         /package/admin/djbwares [pts/4.10022.1]
2 stackexchange.com:
170 bytes, 1+4+0+0 records, response, authoritative, noerror
query: 2 stackexchange.com
answer: stackexchange.com 172800 NS ns-1029.awsdns-00.org
answer: stackexchange.com 172800 NS ns-925.awsdns-51.net
answer: stackexchange.com 172800 NS ns-cloud-d1.googledomains.com
answer: stackexchange.com 172800 NS ns-cloud-d2.googledomains.com
% 
% dnsqr a gbnjk.com
1 gbnjk.com:
27 bytes, 1+0+0+0 records, response, authoritative, nxdomain
query: 1 gbnjk.com
%

The machine-parseable tools are designed to be used in shell scripts. They do not clutter their outputs with extra stuff like "has ipv4 address" or "answer:", and their outputs are well-defined. dnsipq always prints a single line (that is possibly blank) for each input name or exits with a failure code, for example. dnsnamex always prints a single line (that is possibly blank or containing multiple space-separated names) for each input IP address, for another example.

% dnsip unix.stackexchange.com. unix.stockexchange.com.
151.101.129.69 151.101.193.69 151.101.1.69 151.101.65.69 

% 
% dnsnamex `dnsip unix.stackexchange.com.`




% 
% dnsmx unix.stackexchange.com.
0 unix.stackexchange.com
% 
% dnsmx stackexchange.com.
1 aspmx.l.google.com
5 alt1.aspmx.l.google.com
5 alt2.aspmx.l.google.com
10 alt3.aspmx.l.google.com
10 alt4.aspmx.l.google.com
%

As you can see, they are geared towards doing the DNS lookups for specific tasks rather than doing just one DNS transaction of a specific type. dnsmx, for example, reports to where MTSes are to transmit SMTP mail and what order they try in, in a machine-parseable one-result-per-line whitespace-separated form; gathering which information involves more than one DNS transaction.

NLlabs tools

NLlabs's drill from LDNS (not Unbound as another answer has it) is designed to print "even more information than dig" according to its user manual. It does not have an equivalent of dig's short mode. Like dig in normal mode, its output is in the ISC's "zone file" format, complete with copious comment lines, requiring a full "zone file" parser to handle programatically. So it isn't the tool for short machine-parseable output.

Its command-line parsing is rather sloppy:

% drill you can have anything here +short and as much of it as you like '!' unix.stackexchange.com.
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 47385
;; flags: qr rd ra ; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0 
;; QUESTION SECTION:
;; unix.stackexchange.com.  IN  A

;; ANSWER SECTION:
unix.stackexchange.com. 277 IN  A   151.101.193.69
unix.stackexchange.com. 277 IN  A   151.101.129.69
unix.stackexchange.com. 277 IN  A   151.101.65.69
unix.stackexchange.com. 277 IN  A   151.101.1.69

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:

;; Query time: 145 msec
;; SERVER: 127.0.0.1
;; WHEN: Sun May 27 10:52:12 2018
;; MSG SIZE  rcvd: 104
%

Although this sort of thing aids humans who cannot remember whether the type or the domain name is the first argument to the command, it is the opposite of what one wants for scripting purposes. One wants a well-defined interface, with a defined and documented ordering of parameters, where a misuse is an error and that does not attempt to second-guess what one meant to run.

"just DNS"

So as noted in another answer, it depends from what you want by "just DNS".

  • If you want tools with machine-parseable outputs for use in scripts, that output just the resultant information, look to the djbdns toolset.
  • If you want tools that only ever perform just one DNS transaction but give an output that you as a human can read, look at my host or the tools from the djbdns toolset.
  • Otherwise, look at any and all of the aforementioned.

Note that one of the several failings of nslookup is that on several operating systems including some Unices it has been augmented to do more than just DNS lookups alone. nslookup is a seriously flawed tool, as I and others have been explaining for close to two decades, now. It most definitely should not be "the usual tool" and I hope that because of our efforts over the years nowadays it is not.

Further reading

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It depends on what exactly you mean by "just" (compared to what baseline?). host (from the bind-tools or bind-utils package) is pretty terse in its output, but still has a bit of human-readable text around it:

[0 1016 8:16:41] ~ % host unix.stackexchange.com
unix.stackexchange.com has address 151.101.129.69
unix.stackexchange.com has address 151.101.193.69
unix.stackexchange.com has address 151.101.65.69
unix.stackexchange.com has address 151.101.1.69

Part of the "problem" is that there are more cases that can happen that you'd need to signal in output and/or return code, such as: DNS server failure, CNAME entries (i.e. "linux.example.com is whatever unix.example.com is, go look there"):

[0 1018 8:17:36] ~ % host www.latimes.com
www.latimes.com is an alias for 32975.edgekey.net.
32975.edgekey.net is an alias for e11929.e12.akamaiedge.net.
e11929.e12.akamaiedge.net has address 23.219.130.10
e11929.e12.akamaiedge.net has address 23.219.130.8

and probably many more.

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The usual simple tools tool are:

$ host unix.stackexchange.com
unix.stackexchange.com has address 151.101.1.69
unix.stackexchange.com has address 151.101.65.69
unix.stackexchange.com has address 151.101.129.69
unix.stackexchange.com has address 151.101.193.69

$  nslookup unix.stackexchange.com
Server:         127.0.0.1
Address:        127.0.0.1#53

Non-authoritative answer:
Name:   unix.stackexchange.com
Address: 151.101.1.69
Name:   unix.stackexchange.com
Address: 151.101.65.69
Name:   unix.stackexchange.com
Address: 151.101.129.69
Name:   unix.stackexchange.com
Address: 151.101.193.69

The host comes from ISC unbound in bind9-host package. Both dig, and nslookup come from dnsutils package. If you need other tools directed to more detailed analysis of DNS, then there is dig (from bind). A short answer is given with the +short option (remove to get a more verbose answer):

$ dig +short unix.stackexchange.com
151.101.1.69
151.101.65.69
151.101.129.69
151.101.193.69

Or drill (from unbound):

$ drill @1.1.1.1 unix.stackexchange.com
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 48240
;; flags: qr rd ra ; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; unix.stackexchange.com.      IN      A

;; ANSWER SECTION:
unix.stackexchange.com. 250     IN      A       151.101.1.69
unix.stackexchange.com. 250     IN      A       151.101.65.69
unix.stackexchange.com. 250     IN      A       151.101.129.69
unix.stackexchange.com. 250     IN      A       151.101.193.69

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:

;; Query time: 3 msec
;; SERVER: 1.1.1.1
;; WHEN: Sun May 27 10:16:27 2018
;; MSG SIZE  rcvd: 104

Be careful with dig and specially with trusting drill answers if you do not know how to set trust anchors. Both tools are far away from simple.

Related drill if you can, dig if you have to, nslookup if you must

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