Useful 'host' Command Examples for Querying DNS Lookups

Channel: Linux Commands Linux
Abstract: google.com has IPv6 address 2a00google.com has IPv6 address 2a00

Host command is a minimal and easy-to-use CLI utility for performing DNS lookups which translate domain names to IP addresses and vice versa. It can also be used to list and verify various types of DNS records such as NS and MX, test and validate ISP DNS server and Internet connectivity, spam and blacklisting records, detecting and troubleshooting DNS server issues among others.

In this article, we will learn how to use host command with a few useful examples in Linux to perform DNS lookups. In previous articles, we showed the most used 8 Nslookup commands for testing and troubleshooting DNS servers and to query specific DNS resource records (RR) as well.

We also explained 10 Linux Dig (Domain Information Groper) commands to query DNS info, it works more like the Nslookup tool. The host utility also works in a similar way and comes preinstalled on most if not all mainstream Linux distros.

With that said, let’s look at these 14 host commands below.

Find the Domain IP Address

This is the simplest host command you can run, just provide a domain name such as google.com to get the associated IP addresses.

$ host google.com

google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has IPv6 address 2a00:1450:4009:80b::200e
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
Find Domain Name Servers

To find out the domain name servers use the -t option.

$ host -t ns google.com

google.com name server ns1.google.com.
google.com name server ns2.google.com.
google.com name server ns3.google.com.
google.com name server ns4.google.com.
Find Domain CNAME Record

To find out the domain CNAME, run.

$ host -t cname mail.google.com

mail.google.com is an alias for googlemail.l.google.com.
Find Domain MX Record

To find out the MX records for a domain.

$ host -n -t mx google.com

ogle.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
Find Domain TXT Record

To find out the TXT records for a domain.

$ host -t txt google.com

google.com descriptive text "v=spf1 include:_spf.google.com ~all"
Find Domain SOA Record

You can make host attempt to display the SOA records for specified zone, from all the listed authoritative name servers for that zone with the -C flag.

$ host -C google.com

Nameserver 216.239.38.10:
	google.com has SOA record ns1.google.com. dns-admin.google.com. 156142728 900 900 1800 60
Nameserver 216.239.32.10:
	google.com has SOA record ns3.google.com. dns-admin.google.com. 156142728 900 900 1800 60
Nameserver 216.239.34.10:
	google.com has SOA record ns4.google.com. dns-admin.google.com. 156142728 900 900 1800 60
Nameserver 216.239.36.10:
	google.com has SOA record ns2.google.com. dns-admin.google.com. 156142728 900 900 1800 60
Query Particular Name Server

To query particual domain name server.

$ host google.com ns4.google.com

Using domain server:
Name: ns4.google.com
Address: 216.239.38.10#53
Aliases: 

google.com has address 172.217.19.46
google.com has address 172.217.19.46
google.com has address 172.217.19.46
google.com has IPv6 address 2a00:1450:4005:808::200e
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
Find All Information of Domain Records and Zones

To make a query of type ANY, use the -a (all) option which is equivalent to setting the -v option.

$ host -a google.com

Trying "google.com"
;; ->>HEADER<
Get Domain TTL Information

To find out domain TTL information.

$ host -v -t a google.com

Trying "google.com"
;; ->>HEADER<
Use Either IPv4 or IPv6

The -4 or -6 option forces host to use only IPv4 or only IPV6 query transport respectively.

$ host -4 google.com
OR
$ host -6 google.com
Perform Non-Recursive Queries

The -r option performs non-recursive queries, note that setting this option clears the RD (recursion desired), the bit in the query which host makes.

$ host -rR 5 google.com

google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has IPv6 address 2a00:1450:4009:80b::200e
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
Set UDP Retries for a Lookup

By default the number of UDP tries is 1, to change it, use the -R flag.

$ host -R 5 google.com

google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has IPv6 address 2a00:1450:4009:80b::200e
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 10 aspmx.l.google.com.
Set Query Time Wait for Reply

Using the -W switch, you can instruct host to wait for a reply for the specified time in seconds and if the -w flag is used, it makes host to wait forever for a reply:

$ host -T -W 10 google.com

google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has address 216.58.201.46
google.com has IPv6 address 2a00:1450:4009:80b::200e
google.com mail is handled by 10 aspmx.l.google.com.
google.com mail is handled by 40 alt3.aspmx.l.google.com.
google.com mail is handled by 30 alt2.aspmx.l.google.com.
google.com mail is handled by 20 alt1.aspmx.l.google.com.
google.com mail is handled by 50 alt4.aspmx.l.google.com.

That’s it! In this article, we learned how to use host command with a few useful examples in Linux. Use the feedback form below to share any thoughts with us concerning this guide.

Ref From: tecmint
Channels: linux commands

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