DNS for Sysadmins: The Commands and Tools You Actually Need

DNS comes up in sysadmin work constantly. Server migrations, email deliverability issues, "the website isn't loading" tickets, certificate renewals, debugging weird routing problems. You don't need to be a DNS expert, but you do need a solid toolkit. Here's the DNS commands and tools I use regularly, with real examples from actual problems I've dealt with. dig - the workhorse dig is the most useful DNS tool you'll ever learn. It queries DNS servers and shows you exactly what they return, with full detail. Basic lookup dig example.com This queries your system's default DNS resolver for the A record. The output is verbose but everything in it is useful. Query a specific DNS server dig @8.8.8.8 example.com This bypasses your local resolver and asks Google directly. Essential for comparing what different resolvers return. Query specific record types dig example.com MX # Mail servers dig example.com TXT # SPF, DKIM, DMARC, verification records dig example.com NS # Nameservers dig example.co