DNS Propagation Checker

Just changed an A record and your friend in another country still sees the old site? That's DNS propagation. Here's how to verify when it's actually done — and how long it can take.

DNS lookups are the first step in almost every network troubleshooting flow. Here's how they work, the record types that matter, and how to run them from your browser.

An 'open port' isn't a vulnerability by itself — it's information. Here's how to tell whether a port being open is fine, suspicious, or actively dangerous, and what to do about each case.