Host command (Linux), probing your DNS

15.09.2020 39 0

In continuation to our practical set of articles dedicated to different networking software, it is time for the Linux Host Command. You can use it instead of nslookup on your Linux computer.

How to check the syntax of host command?

To see the syntax of host command, do the following:

  1. Open the Terminal
  2. Type host
  3. Press the Enter button

Done. Now you will see this message:

linux@linux:~$ host
Usage: host [-aCdilrTvVw] [-c class] [-N ndots] [-t type] [-W time]
            [-R number] [-m flag] hostname [server]
       -a is equivalent to -v -t ANY
       -c specifies query class for non-IN data
       -C compares SOA records on authoritative nameservers
       -d is equivalent to -v
       -i IP6.INT reverse lookups
       -l lists all hosts in a domain, using AXFR
       -m set memory debugging flag (trace|record|usage)
       -N changes the number of dots allowed before root lookup is done
       -r disables recursive processing
       -R specifies number of retries for UDP packets
       -s a SERVFAIL response should stop query
       -t specifies the query type
       -T enables TCP/IP mode
       -v enables verbose output
       -V print version number and exit
       -w specifies to wait forever for a reply
       -W specifies how long to wait for a reply
       -4 use IPv4 query transport only
       -6 use IPv6 query transport only

What options does host command have?

You can see the options following the same steps. The host command has these options:

Option Description
-a Same as -v -t ANY, shows all records
-c Non-In data specific query class
-d Equivalent to -v
-i For reverse lookups
-l Using AXFR to show list of all hosts in a domain
-m Memory debugging flag
-N Number of dots allowed, before root lookup
-r Stops recursive process
-R Set numbers of retries for UDP packets
-s Stop query if SERVFAIL received
-t Another query specification
-T TCP/IP mode enabled
-v Enable verbose output
-V Print version number and exit
-w Wait forever
-W Wait specific time in sec.
-4 IPv4 only
-6 IPv6 only

Examples of the host command

We’ll use the Yahoo.com for all our examples. You can choose your domain or your competitor’s domain for the probes.

Check the IP address of the targeted domain

The answer will be IPv4 and IPv6 addresses of the target.

linux@linux:~$ host yahoo.com
yahoo.com has address 74.6.231.20
yahoo.com has address 74.6.143.25
yahoo.com has address 74.6.143.26
yahoo.com has address 98.137.11.164
yahoo.com has address 98.137.11.163
yahoo.com has address 74.6.231.21
yahoo.com has IPv6 address 2001:4998:124:1507::f000
yahoo.com has IPv6 address 2001:4998:124:1507::f001
yahoo.com has IPv6 address 2001:4998:44:3507::8001
yahoo.com has IPv6 address 2001:4998:44:3507::8000
yahoo.com has IPv6 address 2001:4998:24:120d::1:0
yahoo.com has IPv6 address 2001:4998:24:120d::1:1
yahoo.com mail is handled by 1 mta5.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta6.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta7.am0.yahoodns.net.

See SOA Record

See the authoritative name server.

linux@linux:~$ host -C yahoo.com
Nameserver 68.180.131.16:
	yahoo.com has SOA record ns1.yahoo.com. hostmaster.yahoo-inc.com. 2020091412 3600 300 1814400 600
Nameserver 68.142.255.16:
	yahoo.com has SOA record ns1.yahoo.com. hostmaster.yahoo-inc.com. 2020091412 3600 300 1814400 600
Nameserver 98.138.11.157:
	yahoo.com has SOA record ns1.yahoo.com. hostmaster.yahoo-inc.com. 2020091412 3600 300 1814400 600
Nameserver 27.123.42.42:
	yahoo.com has SOA record ns1.yahoo.com. hostmaster.yahoo-inc.com. 2020091412 3600 300 1814400 600
Nameserver 202.165.97.53:
	yahoo.com has SOA record ns1.yahoo.com. hostmaster.yahoo-inc.com. 2020091412 3600 300 1814400 600

See all the name servers of a domain

You will see a list of them. We specify the query with “-t”.

linux@linux:~$ host -t ns yahoo.com
yahoo.com name server ns2.yahoo.com.
yahoo.com name server ns3.yahoo.com.
yahoo.com name server ns5.yahoo.com.
yahoo.com name server ns1.yahoo.com.
yahoo.com name server ns4.yahoo.com.

Probe a particular name server

Let’s check out the first sever ns1 by writing:

linux@linux:~$ host yahoo.com ns1.yahoo.com
Using domain server:
Name: ns1.yahoo.com
Address: 68.180.131.16#53
Aliases: 

yahoo.com has address 98.137.11.163
yahoo.com has address 74.6.231.21
yahoo.com has address 74.6.231.20
yahoo.com has address 74.6.143.25
yahoo.com has address 98.137.11.164
yahoo.com has address 74.6.143.26
yahoo.com has IPv6 address 2001:4998:44:3507::8000
yahoo.com has IPv6 address 2001:4998:24:120d::1:1
yahoo.com has IPv6 address 2001:4998:124:1507::f000
yahoo.com has IPv6 address 2001:4998:24:120d::1:0
yahoo.com has IPv6 address 2001:4998:44:3507::8001
yahoo.com has IPv6 address 2001:4998:124:1507::f001
yahoo.com mail is handled by 1 mta6.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta7.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta5.am0.yahoodns.net.

See the canonical record (CNAME)

linux@linux:~$ host -t cname mail.yahoo.com
mail.yahoo.com is an alias for edge.gycpi.b.yahoodns.net.

MX record

To review the incoming mail server use this command:

linux@linux:~$ host -n -t mx yahoo.com
yahoo.com mail is handled by 1 mta7.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta6.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta5.am0.yahoodns.net.

TXT Record

You can see TXT records too:

linux@linux:~$ host -t txt yahoo.com
yahoo.com descriptive text "v=spf1 redirect=_spf.mail.yahoo.com"
yahoo.com descriptive text "facebook-domain-verification=gysqrcd69g0ej34f4jfn0huivkym1p"
yahoo.com descriptive text "edb3bff2c0d64622a9b2250438277a59"

Set the time to wait for an answer

Write “-w” to wait without any limits or “-W” and seconds to set a specific waiting time for a response of a query.

linux@linux:~$ host -T -W 10 yahoo.com
yahoo.com has address 74.6.231.21
yahoo.com has address 98.137.11.163
yahoo.com has address 98.137.11.164
yahoo.com has address 74.6.143.26
yahoo.com has address 74.6.143.25
yahoo.com has address 74.6.231.20
yahoo.com has IPv6 address 2001:4998:24:120d::1:1
yahoo.com has IPv6 address 2001:4998:24:120d::1:0
yahoo.com has IPv6 address 2001:4998:44:3507::8000
yahoo.com has IPv6 address 2001:4998:44:3507::8001
yahoo.com has IPv6 address 2001:4998:124:1507::f001
yahoo.com has IPv6 address 2001:4998:124:1507::f000
yahoo.com mail is handled by 1 mta7.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta6.am0.yahoodns.net.
yahoo.com mail is handled by 1 mta5.am0.yahoodns.net.

Reverse lookup

Start from the IP address and find the host.

linux@linux:~$ host 98.137.246.7
7.246.137.98.in-addr.arpa domain name pointer media-router-fp71.prod.media.vip.gq1.yahoo.com.

All DNS records with this host command

Get a long list of DNS records and valuable information for them.

linux@linux:~$ host -a yahoo.com
Trying "yahoo.com"
Trying "yahoo.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48527
;; flags: qr rd ra; QUERY: 1, ANSWER: 23, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;yahoo.com.			IN	ANY

;; ANSWER SECTION:
yahoo.com.		1214	IN	TXT	"facebook-domain-verification=gysqrcd69g0ej34f4jfn0huivkym1p"
yahoo.com.		1214	IN	TXT	"edb3bff2c0d64622a9b2250438277a59"
yahoo.com.		1214	IN	TXT	"v=spf1 redirect=_spf.mail.yahoo.com"
yahoo.com.		368	IN	AAAA	2001:4998:124:1507::f000
yahoo.com.		368	IN	AAAA	2001:4998:44:3507::8000
yahoo.com.		368	IN	AAAA	2001:4998:124:1507::f001
yahoo.com.		368	IN	AAAA	2001:4998:44:3507::8001
yahoo.com.		368	IN	AAAA	2001:4998:24:120d::1:1
yahoo.com.		368	IN	AAAA	2001:4998:24:120d::1:0
yahoo.com.		329	IN	MX	1 mta6.am0.yahoodns.net.
yahoo.com.		329	IN	MX	1 mta7.am0.yahoodns.net.
yahoo.com.		329	IN	MX	1 mta5.am0.yahoodns.net.
yahoo.com.		512	IN	A	98.137.11.164
yahoo.com.		512	IN	A	74.6.143.25
yahoo.com.		512	IN	A	74.6.231.20
yahoo.com.		512	IN	A	74.6.231.21
yahoo.com.		512	IN	A	74.6.143.26
yahoo.com.		512	IN	A	98.137.11.163
yahoo.com.		98741	IN	NS	ns3.yahoo.com.
yahoo.com.		98741	IN	NS	ns2.yahoo.com.
yahoo.com.		98741	IN	NS	ns1.yahoo.com.
yahoo.com.		98741	IN	NS	ns4.yahoo.com.
yahoo.com.		98741	IN	NS	ns5.yahoo.com.

Received 625 bytes from 127.0.0.53#53 in 5 ms

Conclusion

Another handy software for network diagnostic, this time for Linux users. It is perfect for keeping an eye on your domain and its performance.

Source: https://www.geeksforgeeks.org/host-command-in-linux-with-examples/

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