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How to get a hostname/domain name from an IP address in Linux

One of the questions that many Linux users ask is how they can retrieve a system’s hostname using its IP address. It may seem an uphill task, but in the real sense, it’s quite easy. Essentially, this is known as the reverse DNS lookup. Reverse DNS lookup queries an IP address to retrieve the hostname or domain of the server. The exact opposite is the Forward DNS lookup which maps the domain name to the IP address.

In this short guide, we have explored a few ways to performs Reverse DNS lookup and get a domain name from an IP address. For demonstration purposes, I have used Ubuntu 20.04.

Prerequisites

Before you roll up your sleeves, ensure that your remote host has an A record which is a DNS entry that points or maps a domain name to an IP address

Perform DNS Reverse lookup using dig command

Dig command is a flexible and powerful tool that is used for querying or probing DNS records. It’s an acronym for domain information groper and allows you to retrieve a wide array of DNS information such as A, CNAME, MX, and SOA records.

Perform DNS Reverse lookup using nslookup command

A nslookup command is a troubleshooting tool that features highly in a sysadmin’s armory. It’s a versatile tool that performs all DNS record querying such as CNAME, A, MX, and reverses or PTR records.

To retrieve a domain name from an IP address, use the command syntax:

Perform DNS Reverse lookup using the host command

Similarly, you can use the host command to obtain a hostname or domain name from an IP address using the syntax as shown.

For example, to check the domain name for the IP 5.9.235.235, execute the command:

Just like the Nslookup command, you can also use the host command with hostnames or IP addresses.

Conclusion

The few examples that we have just elaborated are a sure way of helping you obtain the domain name from an IP address. Usually, the reverse DNS lookup is trivial and not as crucial as the forward lookup, which maps domain names to IP addresses. Your feedback or contribution will be highly welcomed.

About the author

Karim Buzdar

Karim Buzdar holds a degree in telecommunication engineering and holds several sysadmin certifications. As an IT engineer and technical author, he writes for various web sites. He blogs at LinuxWays.

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Find Hostname from IP Linux

Names or labels are useful as they allow us to identify one thing or one person from another. Even a person’s name, which might not be globally unique, contains a set of characters that allow a person to become distinguished from another person.

Similarly, computers support labels or names that help give them a unique identity in a network. That is where a hostname comes in. A hostname is a set of alphanumerical characters unique to a computer network, allowing devices to communicate with each other.

Typically, the underlying technology that identifies a computer or a device in a network is a set of numbers known as IP addresses. These are then mapped to a specific name resolved to the IP address of the machine.

In this tutorial, however, I will show you various ways that you can use to get the hostname associated with a specific IP address. The methods discussed in this tutorial will work in almost all Linux and Unix-Like systems.

If you are looking for detailed instructions on how systems such as Domain Names work, check out the resource on the link provided below:

With that out of the way, let us dive in.

Method 1: Ping

The simplest method to get the hostname from an IP address is to use ping. Ping is a simple yet powerful command-line utility that uses ECHO packets to communicate with a host.

NOTE: The following command only works in Windows machines. For Linux, check the next method.

To get a hostname from an IP address with ping, use the command below:

Here is the output from the above command:

The above command is not always reliable; it often only works if the hostname is available in the hosts file.

Method 2: Host Command

The second and common method for getting the hostname from the IP address in Linux is the host command. This simple tool is part of the dnsutil package.

To install the package, use the commands:

Ubuntu/Debian-based distros

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How to Use the hostname Command in Linux

The Linux hostname command is used to view or change a system’s domain and hostname. It can also check a computer’s IP address.

In this tutorial, we will cover all the ways you can use the hostname command on Linux and how to change your computer’s hostname on a Linux system.

hostname Command Syntax

The hostname command uses the following format:

hostname [options] [new_hostname]

Use the [options] parameter to add more specific instructions to the hostname command. Without it, the default output shows your computer’s hostname:

Use the [new_hostname] parameter when you want to change your computer’s hostname.

hostname Command Examples

The hostname command has a number of options you can use for more specific outputs:

• -a , —alias : Displays the alias name of the host.
• -A , —all-fqdns : Displays every FQDN (Fully Qualified Domain Name) of the computer.
• -b , —boot : Always set a hostname.
• -d , —domain : Display DNS domain name.
• -f , —fqdn , —long : Display the FQDN.
• -F , —file : Check a file to recover and display the hostname.
• -h , —help : Print the help message as the output.
• -i , —ip-address : Display the computer’s IP address.
• -I , —all-ip-addresses : Display all of the computer’s network addresses.
• -s , —short : Display the short version of the hostname.
• -v , —verbose : Expand all output to verbose.
• -y , —yp , —nis : Display the NIS domain name.

Display Hostname

Using the hostname command without any additional options displays the computer’s hostname:

Display Short Hostname

Use the -s or —short option to display the short version of the hostname, which is cut off at the first dot:

hostname -s hostname --short

Display Alias

Use the -a or —alias option to display the alias (substitute hostname) of the host if one is set. There are very few cases where this option is useful, and its use is no longer recommended.

hostname -a hostname --alias

Search for Hostnames

Use the -F or —file option to search a specific file (such as hostname or hosts) and change your computer’s hostname to match the content of the file:

sudo hostname -F [file path] sudo hostname --file [file path]

Note: When using the -F or —file options, also specify the path to the file you want to check.

Force Default Hostname

If you don’t want to have a specific file containing the hostname, or want to leave that file empty, use the -b or —boot option. This makes your computer use the default hostname (localhost) until you set a different one:

Display Domain Name

Use the -d or —domain option to display the name of your DNS domain:

hostname -d hostname –domain

Display FQDN

If you want to display a system’s FQDN, use the -f , —fqdn , or —long option:

hostname -f hostname --fqdn hostname --long

A FQDN contains the short hostname and the DNS domain name.

Display All FQDNs

To display each FQDN of your machine, use the -A or —all-fqdns option:

hostname -A hostname --all-fqdns

This option lists out all of your network addresses and their DNS domain names. It skips any addresses that it can’t translate.

Note: Different network addresses may translate to same DNS domain names. This can result in duplicate output entries when using -A or —all-fqdns options.

Display NIS Domain

If you’re using NIS (Network Information Service), you can check your NIS domain name with the -y , —yp , or —nis option:

hostname -y hostname --yp hostname --nis

Change NIS Domain Name

Use this command with the following format to change your NIS domain name:

sudo hostname -y [NIS hostname] sudo hostname --yp [NIS hostname] sudo hostname --nis [NIS hostname]

Display Related Network Addresses

The hostname command also lets your display network addresses tied to a hostname. To do this, use the -i or —ip-address option:

hostname -i hostname --ip-address

This command only works if the hostname can be resolved.

Display All Network Addresses

Use the -I or —all-ip-addresses option to display all of the host’s network addresses. Unlike -i , this option doesn’t depend on hostname resolution:

hostname -I hostname --all-ip-addresses

Change Hostname Until Reboot

You can change your computer’s hostname with the hostname command. To do this, use the following format:

sudo hostname [new hostname]

Any changes to the hostname you make using this command will only last until the next reboot.

Change Hostname Permanently

To change the hostname permanently, use a text editor like Nano to make changes to the hostname and hosts files:

sudo nano /etc/hostname sudo nano /etc/hosts

You can also use the hostnamectl command to permanently change the hostname:

sudo hostnamectl set-hostname [new hostname]

Additional hostname Options

Use the -V or —version option to print out the version of the hostname software package on your Linux system:

hostname -V hostname --version

If you need help with any of the commands, use the -h or —help option to print out a help message:

After following this guide, you now know how to use the hostname command in Linux and all the options that can extend its use.

For more Linux commands, check out our Linux Commands Cheat Sheet.

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