DNS fundamentals, troubleshooting, security, and practical workflows -- written by the team that builds this tool.
How an email finds your mail server
Sender
you@gmail.com
MX lookup
who takes mail?
Mail server
priority 10 first
Inbox
delivered
Lowest priority number wins; higher numbers are backups
What is an MX record? It decides where your domain's email lands: how priority numbers work, what null MX means, and the mistakes that silently lose messages.
The records you will meet in nearly every zone
The decision comes down to one question: do you control the IP address, or does someone else? Plus the root-domain rule that trips everyone up.
The records you will meet in nearly every zone
The record that actually points your domain at a server — its anatomy, the AAAA counterpart, and the four mistakes that break sites most often.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
What is the IP address of a website? Five ways to find the IP address of any website or URL, with exact commands for Windows, macOS, and Linux.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
The internet's phone book, traced end to end: what happens in the few milliseconds between typing a domain and the first packet reaching a server.
Two addressing schemes, running side by side
IPv4
192.0.2.10
32 bits -- ~4.3 billion addresses -- exhausted
IPv6
2606:4700::6810:84e5
128 bits -- 340 undecillion addresses
The numeric label behind every website, server, and phone on the internet — what it means, how to read it, and why there are two incompatible versions.
Two genuinely different moments
dig / nslookup
Full protocol detail, scriptable, offline
Web-based tool
No setup, bulk lookups, shareable
The terminal tools aren't going anywhere, and a web tool isn't trying to replace them -- they're suited to genuinely different moments.
Picking the right export
CSV
Spreadsheet analysis, filtering, pivot tables
JSON
Scripts and automated diff pipelines
Once a bulk DNS lookup has resolved a few thousand domains, the interesting work is what you do with the export -- a practical guide to that step.
Matching cadence to what's being watched
A recurring lookup job catches DNS drift automatically -- here's how to think through what to check and how often.
Four steps, checked in order
Export
every current record
Migrate
to the new provider
Verify
compare every record
Confirm
wait out the old TTL
A practical checklist for confirming a DNS provider switch or record migration actually completed, rather than assuming it did.
Two addressing schemes, running side by side
IPv4
192.0.2.10
32 bits -- ~4.3 billion addresses -- exhausted
IPv6
2606:4700::6810:84e5
128 bits -- 340 undecillion addresses
The world ran out of new IPv4 addresses years ago. Here's what's actually kept things running since, and why the transition still isn't done.
Signals worth an alert
Watching one domain's DNS by hand doesn't scale to dozens or thousands. Here's a practical approach to catching changes early.