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How to Find My DNS Server IP Address in Linux

DNS (Domain Name System) is a fundamental facilitator of several networking technologies such as mail servers, Internet browsing, and streaming services e.g. Netflix and Spotify, among others.

It works on a special computer called a DNS server – which keeps a database record of several public IP addresses along with their corresponding hostnames in order for it to resolve or translate hostnames to IP addresses upon user request.

This happens so that we would not need to bother ourselves with remembering the IP addresses of the different websites we visit.

While there are several things we can discuss on DNS servers such as redirection and malware attack prevention, our focus today is on how to find out your very own dns server IP address.

There are several ways to check for it depending on the Operating System that you’re running but Linux, BSD, and Unix-like systems all share the same method so let’s begin with them.

How to Find My DNS Server IP Address

1. To find out your DNS Server IP address, use the following cat command or less command.

2. Another way is to use the following grep command.

Here, nameserver 109.78.164.20 is a name server IP address in what is called the dot notation – the format that applications on your workstation use for DNS routing.

How to Find My Website DNS Server IP Address

3. To find out a website DNS Server IP address, you can use the following dig command.

Sample Output

Easy right? Perhaps we’ll talk about primary and secondary DNS Server addresses next time. Till then, feel free to share and drop your comments/suggestions in the discussion section below.

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Просмотр и изменение DNS в Linux

Служба DNS (англ. Domain Name System — система доменных имён) используется для получения информации о доменах. Основное её предназначение — увязывать IP-адрес и доменное имя хоста. Посмотреть, к какому DNS-серверу подключен компьютер с Linux на борту, не просто, а очень просто. Как просто и поменять DNS в Linux.

Если Linux снабжён графическим интерфейсом, достаточно открыть сведения о сетевом соединении и посмотреть в строчку DNS.

По понятным причинам нас этот способ не очень интересует. Да и элементы интерфейса могут у разных сред рабочего стола различаться. Рассмотрим просмотр и настройку DNS в терминале Linux.

Традиционно DNS в Linux настраивалась через файл /etc/resolv.conf. Сейчас, однако, он может оказаться бесполезным. Откроем его любым консольным текстовым редактором, например nano:

Мы можем увидеть следующее:

Это значит, что в системе есть systemd, который содержит свой локальный сервер DNS. Его адрес и прописан в этом файле. Однако, в конечном итоге, используются другие DNS-серверы! Посмотреть их можно по-разному. Можно использовать команду

Вы увидите нечто подобное тому, что на скриншоте ниже. Если в системе несколько сетевых интерфейсов, информация будет предоставлена по каждому.

Другой способ — использовать утилиту nmcli. Введите команду

Как изменить DNS? Если в системе нет systemd, то это можно сделать редактированием файла /etc/resolv.conf. Откройте его любым текстовым редактором, найдите строку nameserver и впишите адреса DNS-серверов. Если их несколько, введите их адреса последовательно. Например:

Если в ОС есть systemd, вышеописанных способ бесполезен, поскольку настройки будут перезаписываться при перезагрузке системы. В данном случае нам нужно редактировать файл /etc/systemd/resolved.conf.

В разделе Resolve отредактируйте строку DNS. При необходимости уберите символ # для раскомментирования. Адреса DNS-серверов прописываются через запятую.

Как видим на этом примере, systemd несколько усложнил операционную систему Linux. Однако настроить DNS в ней до сих пор не составляет труда. Кроме того, в Linux можно пользоваться и файлом hosts.

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Как посмотреть DNS в Linux

Служба DNS или Domain Name System позволяет превращать легко читаемый адрес сайта в ip адрес сервера на котором расположен этот сайт. Для этого используются DNS серверы, которые содержат таблицы соответствия ip адресов их доменным именам. По умолчанию система получает адрес DNS сервера автоматически по DHCP при подключении к сети.

В этой статье мы разберемся как посмотреть какие DNS серверы используются в Linux.

Как посмотреть DNS в Linux

Если вы уже имели опыт настройки сети в Linux, то знаете, что DNS серверы, используемые для резолвинга доменных имен указаны в файле /etc/resolv.conf:

sudo vi /etc/resolv.conf

Но в современных дистрибутивах Linux с системой инициализации systemd обычно запущен локальный DNS сервер, адрес которого и прописан в этом файле, а какие сервера используются на самом деле непонятно. В таком случае можно воспользоваться утилитой systemd-resolve:

В самом низу вывода утилиты можно посмотреть DNS в Linux, которые сейчас используются. Информация выводится по каждому сетевому интерфейсу отдельно.

Также для решения подобной задачи можно использовать утилиту nmcli:

nmcli dev show | grep DNS

Как видите, все очень просто. А чтобы изменить DNS сервер тоже трогать /etc/resolv.conf не желательно, так как он будет автоматически обновляться после перезагрузки. Если вы используете NetworkManager, то можно настроить DNS для сетевого подключения в интерфейсе программы. Или же можно отредактировать файл /etc/systemd/resolved.conf и добавить нужные адреса в секцию Resolve:

sudo vi /etc/systemd/resolved.conf

[Resolve]
DNS=8.8.8.8, 8.8.4.4

Как видите, все очень просто. Надеюсь, эта информация была вам полезной.

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3 Ways to check DNS records from Linux terminal

There are many third party websites that can verify a domain’s DNS records.

It can also be done from Linux terminal. Why not try yourself, instead of using 3rd party sites?

NIX users spend more time on terminal and looking for a viable option from the terminal for any purpose.

This will be useful not only for me, but also for others looking for a way to do their daily activities at the terminal.

Domain DNS information can be verified from the Linux terminal using the following three commands.

• host Command
• dig Command
• nslookup Command

Use one of the below command to verify domain owner information from the Linux terminal.

What’s Domain Name System (DNS)?

DNS stands for Domain Name System or Domain Name Servers which translates Internet domain and host names to IP addresses and vice versa.

DNS is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network.

It’s basically a set of mapping files that tell the DNS server which IP address each domain or host is associated with, and how to handle requests sent to each domain.

It stores various information about a domain & host such as A, AAAA, CNAME, MX, PTR, NS, SOA, SRV, TXT, and NAPTR.

A Record : A record stands for Address record. The ‘A’ record specifies the IP address (IPv4) of a host. Whenever DNS server get a query to resolve domain-name, it will refer the A record to answer the IP address.

AAA Record : The ‘AAA’ record specifies the IP address (IPv6) of a host.

NS Record : NS Record stands for Name Server record. NS Records maps a domain name to a list of authoritative DNS servers.

MX Record : MX Record stands for mail exchange record. MX Records maps a domain name to a list of mail exchange servers.

PTR Record : PTR record stands for Reverse lookup record or Pointer record. A PTR record maps the IP address to a specific host.

CNAME Record : CNAME Record stands for Canonical Name. CNAME record is used to create aliases that point to other names such as WWW, FTP, MAIL & subdomains to a domain name. Example : a CNAME record can associate the subdomain www.2daygeek.com with 2daygeek.com

SOA Record : SOA record stands for Start of Authority records. SOA records contain information about a DNS zone such as Primary nameserver, Hostmaster E-mail address, zone file seriel number, zone transfer interval and zone expiry details.

TXT Record : TXT Record stands for text record. A TXT record is a type of DNS record that provides text information to sources outside your domain. The text can be either human-or machine-readable and can be used for a variety of purposes.

SPF Record : SPF Record stands for Sender Policy Framework. SPF is an extension to the SMTP mail protocol which is used for e-mail authentication.

SPF record is used to verify whether the message came from an authorized mail server or not. SPF is designed to detect SPAM & PHISHING mail sender’s IP address which was included in the e-mail headers.

DKIM Record : DKIM record stands for Domain Keys Identified Mail. DKIM is an email validation system designed to detect email spoofing by providing encryption authentication to receiving mail exchangers.

It will check whether the incoming mail domain is authorized by the domain’s administrators and that the email (including attachments) has not been modified during transport.

A digital signature included with the message can be validated by the recipient using the signer’s public key published in the DNS.

1) How to verify a domain’s DNS records using the dig command

dig command stands for “domain information groper”. It is a flexible tool for interrogating DNS name servers. It performs DNS lookup and displays the answers that are returned from the name server(s) that were queried.

Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than dig.

2) Checking DNS records of a domain using nslookup command

nslookup command is a program to query Internet domain name servers. Nslookup has two modes interactive and non-interactive.

Interactive mode allows the user to query name servers for information about various hosts and domains or to print a list of hosts in a domain.

Non-interactive mode is used to print just the name and requested information for a host or domain. It’s a network administration tool which will help them to check and troubleshoot DNS related issues.

3) How to check DNS records of a domain using host command

host command is a simple utility for performing DNS lookup. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, host prints a short summary of its command line arguments and options as shown below:

Closing Notes

We have shown you three commands to find DNS records of a domain in Linux.

If you have any questions or feedback, feel free to comment below.

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Linux for Network Engineers: How to Resolve a Host and Test DNS Servers

DNS resolution is one of the most basic functionalities on any host. On Linux, there are multiple ways to test if DNS works, and in this post we’ll review how DNS servers are configured and what commands you can use to test them.

DNS server configuration

Every host needs to have a list of DNS server IPs, and, in most cases, this list comes from the DHCP lease. To see which DNS servers your Linux box is configured with, you have to look at the file “/etc/resolv.conf” as follows:

Local domain name: local.netbeez.net

If you try to resolve an address that has no dots in it (e.g. webpage1), then the resolver will automatically append local.netbeez.net (webpage1.local.netbeez.net) and try to resolve it. When the hostname of the machine contains a ‘.’ (e.g. raspberry.local.netbeez.net) then the local domain name becomes the suffix (local.netbeez.net) of the hostname.

Default search domain: local.netbeez.net and attlocal.net

This is like a superset of the local domain name. You can specify up to 6 domains with a total of 256 characters. If “webpage1”, the resolver will automatically append local.netbeez.net (webpage1.local.netbeez.net) and try to resolve it. If this fails, it will then try attlocal.net (webpage1.attlocal.net).

Nameservers: 8.8.8.8, 192.168.0.1

These are the DNS servers used to resolve web addresses. You can list up to three, and the resolver tries each of them, one by one, until it finds one that works. You may recognized the Google DNS server 8.8.8.8, and 192.168.0.1 is my home router, which also works as a DNS server.

Of course, you’d have to set up your DHCP server to provide all this information to every DHCP request. But you are also able to edit /etc/resolv.conf and change those values. Keep in mind that they will be overwritten the next time a new DHCP lease is provided – unless you specify a static IP configuration on the agent (we’ll cover that in a future post).

How to resolve a URL

Now let’s see how we can test if DNS is working. We’ll also cover how to test specific DNS servers to see if they work and, if so, how fast they are.

There are several commands to do this, but below I will review the most common ones. If any of the following commands are not available on your Linux host, then install them with the following command:

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