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perform-a-dns-lookup.md

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Perform A DNS Lookup

Category: Linux

Linux/Unix/macOS provide the ability to lookup server details from the command line using the host command.

Find the IP address associated with a domain name

For a given domain name, lookup the DNS to resolve to an IP address.

host www.google.com

Prints the following:

www.google.com has address 172.217.25.164
www.google.com has IPv6 address 2404:6800:4006:804::2004

Adding -v to the command will print out verbose information.

Note: Not all servers on the internet can be resolved into IP addresses by these commands.

Find the domain name associated with an IP address

For a given IP address, perform a reverse lookup to determine the domain name for an IP address if the host can be resolved.

host 172.217.25.164

Prints the following:

164.25.217.172.in-addr.arpa domain name pointer syd09s13-in-f4.1e100.net.
164.25.217.172.in-addr.arpa domain name pointer sin01s16-in-f4.1e100.net.
164.25.217.172.in-addr.arpa domain name pointer syd09s13-in-f164.1e100.net.

Note: In some cases, the IP address lookup might resolve to a Content Delivery Network (CDN) or edge server.

Alternative commands

Alternatives to using host for resolving a domain name include nslookup and dig.