Dns

DNS configuration, troubleshooting, and command-line lookup tools.

nslookup command querying DNS records in a Linux terminal

May 25, 2026 • 8 min read

nslookup Command in Linux: Query DNS Records

The nslookup command queries DNS servers for domain records. This guide covers A, MX, NS, TXT, and AAAA lookups, reverse DNS, interactive mode, and choosing a specific name server.

Dig command querying DNS records in a Linux terminal

May 25, 2026 • 12 min read

dig Command in Linux: DNS Lookup

The dig command is a DNS lookup tool for querying name servers. This guide covers querying record types, reverse lookups, tracing resolution paths, and verifying DNSSEC.

Querying domain registration with the whois command in Linux

May 25, 2026 • 7 min read

whois Command in Linux: Query Domain Registration Info

The whois command looks up domain registration, registrar, name server, expiry, IP allocation, and AS number details from Linux.

May 8, 2026 • 8 min read • series

Install and Integrate Rspamd on Ubuntu 26.04

Install Rspamd on Ubuntu 26.04, connect it to Postfix as a milter, configure Redis, and publish DKIM and DMARC records for your mail domain.

Rspamd mail filtering and DKIM signing illustration

May 8, 2026 • 9 min read • series

Set up PostfixAdmin on Ubuntu 26.04

Set up PostfixAdmin on Ubuntu 26.04 with Nginx, PHP, MySQL, DNS records, and a Let's Encrypt certificate for a virtual mail server.

PostfixAdmin dashboard illustration with mailboxes and aliases

Mar 12, 2026 • 7 min read

How to Edit Your Hosts File on Linux, Windows, and macOS

The hosts file maps domain names to IP addresses locally, overriding DNS. This guide explains how to edit /etc/hosts on Linux, macOS, and Windows with examples for testing, blocking, and local development.

Aug 21, 2019 • 4 min read

How to Set DNS Nameservers on Ubuntu 18.04

The DNS nameservers (resolvers) are servers which are used by other devices to perform DNS lookup for a requested domain. In this guide, we’ll explain how to configure the DNS nameservers (resolvers) on Ubuntu 18.04.

Set/Change DNS nameservers on Ubuntu 18.04