Red hat linux nslookup

How to Install and Use dig and nslookup Commands in Linux

In this article, you will learn how to install the dig command and nslookup command on Linux. These commands are used for network troubleshooting and gathering information about domain names.

Dig, short for Domain Information Gopher, is a DNS lookup utility used for probing DNS servers and troubleshooting problems associated with DNS servers. Due to its ease of use, system administrators rely on the tool to troubleshoot DNS issues.

Nslookup is used for handling DNS lookups and displays crucial information such as MX records, and the IP address associated with a domain name.

Newer Linux system ship both dig and nslookup utilities by default. However, older Linux systems may not. The two come bundled inside the bind-utils package.

Let’s see how we can install DNS troubleshooting utilities in Linux.

On this page:

Installing dig & nslookup in CentOS/RHEL

On Red Hat Linux /CentOS, install dig and nslookup using the dnf command.

Upon successful installation, verify the version using the command below.

Installing dig & nslookup on Debian / Ubuntu

On Debian and any of its derivatives including Debian, the installation is done using the apt command.

Again, to verify the installation, run the command.

Installing dig & nslookup on ArchLinux

For ArchLinux, the command for installing dig and nslookup will be.

To check the version of dig installed, run.

Using the dig command

dig command can be used to query a domain name and retrieve information as shown:

The command displays a host of information such as the version of the dig command utility, the DNS server, and its corresponding IP address.

Sample Output

; > DiG 9.11.3-1ubuntu1.9-Ubuntu > fossmint.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER
To get more specific and display only the IP of the domain name append the +short argument as shown:
# dig fossmint.com +short 104.17.179.254 104.17.171.254
 
To check the MX record of the domain name run.
 
# dig fossmint.com MX +short 50 mx3.zoho.com. 20 mx2.zoho.com. 10 mx.zoho.com.
 
Using the nslookup Command
 
To retrieve information about a domain name using the nslookup utility, use the following command.
 
Sample Output
 
Server: 127.0.0.53 Address: 127.0.0.53#53 Non-authoritative answer: Name: fossmint.com Address: 104.27.179.254 Name: fossmint.com Address: 104.27.171.254 Name: fossmint.com Address: 2606:4700:30::681b:b0fe Name: fossmint.com Address: 2606:4700:30::681b:b1fe
 
Conclusion
 
In this article, you learned how to install dig and nslookup command utilities in different Linux distributions and also the basic usage of the commands. We do hope that you can now comfortably install the utilities when confronted with a system without them.
 
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The nslookup Command on Linux
 
The nslookup command is a tool used to query Domain Name System (DNS) servers and retrieve information about a specific domain or IP address. This command is an essential tool for network administrators and system engineers as it can be used to troubleshoot DNS issues and gather information about DNS configurations. In this article, we'll explore the nslookup command on Linux in depth, including its syntax, options, and examples of how it can be used to troubleshoot DNS issues. We will also discuss the prerequisites for using the nslookup command and how to install it on various Linux distributions.
 
Prerequisites
 
To use the “nslookup” command, you need to access the control row interface and an Internet connection. Furthermore, if you are not familiar with the types of DNS record, it is recommended to read "types of DNS records explained" before immersing yourself in this article.
 
nslookup syntax
 
The nslookup command can be used in two modes: interactive and non-interactive. To start nslookup interactive mode, type only the command name −
 
This will provide a prompt that will allow you to run more queries on the server. For example, you can type a domain name and receive information about it.
 
In interactive mode, you can specify an option on a separate line before the query. This option is preceded by "set" −
 
To exit interactive mode, type −
 
Quiet mode allows you to use nslookup to run individual queries. The syntax for quiet mode is −
 
$ nslookup [options] [domain-name]
 
Nslookup options
 
The nslookup command has several switches that can be used to retrieve more detailed information about a domain or IP address. Some of the more commonly used options include −
 
 
-domain=[domain-name] − Change the default DNS name.
 
-debug − Show debugging information.
 
-port=[port-number] − Specify the port for queries. The default port number is 53.
 
-timeout=[seconds] − Specify the time allowed for the server to respond.
 
-type=a − View information about the DNS A address records.
 
-type=any − View all available records.
 
-type=hinfo − View hardware-related information about the host.
 
-type=mx − View Mail Exchange server information.
 
-type=ns − View Name Server records.
 
-type=ptr − View Pointer records. Used in reverse DNS lookups.
 
-type=soa − View Start of Authority records.
 
 
Installing nslookup
 
nslookup is pre-installed on most major operating systems. However, if you need to install it on a Linux distribution that uses the APT package manager, such as Ubuntu, you can install the dnsutils package by running the following command −
 
$ sudo apt install dnsutils -y
 
On CentOS, Fedora and Red Hat, nslookup is part of the bind-utils package. You can install it by running the following command −
 
$ sudo dnf install bind-utils
 
How to use nslookup
 
The nslookup command can be used to perform various types of DNS and reverse DNS lookups, as well as troubleshoot server-related issues. Some common uses of the command include −
 
View NS records for a domain: To view NS records for a domain, type −
 
$ nslookup -type=ns [domain name]
 
View MX records for a domain − MX records store all relevant data from the Mail Exchange server. To check the MX data for a domain, type −
 
$ nslookup -type=mx [domain name]
 
Perform a reverse DNS lookup − To find the domain name associated with an IP address, type −
 
Change the default DNS server − To query a specific DNS server, specify its IP address after the domain name or IP address you want to query. For example, to query the DNS server at the IP address 1.1.1.1 for information about the domain "example.com", type the following command −
 
View all available logs − To view all available logs, type the following command −
 
$ nslookup -type=any example.com
 
DNS troubleshooting − The nslookup command can be used to troubleshoot DNS problems, such as troubleshooting DNS server errors or identifying the cause of slow DNS resolution. The command can also be used to verify that a specific DNS server is responding to queries or to check the status of a DNS zone transfer.
 
DNS Server Test − The nslookup command can be used to test the connectivity and response time of a specific DNS server. When using the command with the "-timeout" and "-port" options, it is possible to specify a personalized time and a personalized door to test the response times and the connectivity of the server. In addition, you can use the "-DEbug" option to show further information and solve any problem with the connection.
 
View DNS records − using the various "-type" options, you can recover specific DNS records such as A, MX, NS, PTR, Soa and Hinfo. This can be useful when solving problems with specific types of DNS records or when they collect INF
 
It is important to keep in mind that the output of the nslookup command will show the "authorized response" and the "non -authoritative response", the authorized response refers to the response provided by one of the names of the names that belongs to the domain is required and no authoritative response It is provided by a server named not associated with specific domain, for example its server named ISP.
 
Conclusion
 
The nslookup command is a powerful tool that can be used to query DNS servers and retrieve information about domain names and IP addresses. It is commonly used by network administrators and system engineers to troubleshoot DNS-related issues, gather information about DNS configurations, and test DNS server connectivity and response time. By understanding the syntax, options and examples of how to use the nslookup command, you can easily troubleshoot DNS issues and retrieve important information about domains and IP addresses.
 
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