#DNS

Encrypt your DNS lookups with a DoH server so your ISP cannot easily see which sites you visit.

Purge cached DNS lookups so Windows re-resolves hostnames from scratch — the fix for 'the new server is live but my browser still hits the old one'.

Look up A, MX or TXT records for any domain and test against a specific DNS server like 8.8.8.8.

Open the hosts file in Notepad as administrator, or append an entry with Add-Content.

Resolve a domain manually and see which DNS server answers — the first test when a site won't load.

Point a domain to 127.0.0.1 so every browser on this Mac fails to reach it.

Point a Wi-Fi or wired profile at faster or privacy-friendly resolvers like 1.1.1.1.

Use networksetup -setdnsservers to set, inspect, or reset DNS servers for any macOS network service.

Read the configured DNS servers for Wi-Fi or Ethernet with networksetup -getdnsservers.

On systemd-based Linux (Ubuntu, Fedora, Debian 12+), the local DNS stub cache is managed by systemd-resolved — and the command to clear it is easy to forget because it changed from systemd-resolve.

Set custom DNS resolvers on a specific interface, or reset them to DHCP defaults, with one cmdlet instead of the network settings GUI.

Use nslookup's classic two-argument form to query a chosen resolver and inspect record types.