Verifying host IP settings

Every TCP/IP capable OS ships both GUI and CLI tools for viewing and setting IPv4 config. Know where they live on the big three.

Static vs dynamic first

Static is typed in by hand and stays put. Dynamic is handed out automatically (DHCP) and can change over time.

A lease may survive a reboot, so don’t count on it changing every restart, but never count on it staying the same either.

Windows

GUI: Network and Sharing Center, then adapter, Properties, Internet Protocol Version 4 (TCP/IPv4), Properties. Radio buttons toggle between DHCP and a manual address, mask, gateway, and DNS.

CLI:

ipconfig        # IP, mask, default gateway per adapter
ipconfig /all   # adds MAC, DHCP server, lease times, DNS

The output also shows the IPv6 link-local (fe80::…) and “Media disconnected” for dead adapters.

macOS

GUI: Apple menu, System Preferences, Network, pick the connection, Advanced, TCP/IP tab. (Newer macOS renamed this to System Settings, same idea.)

CLI: open Terminal (Go > Utilities > Terminal), then:

ifconfig en1    # IP, netmask (shown in hex, 0xffffff00 = /24), broadcast, MAC

Linux

ifconfig plays the same role ipconfig plays on Windows: interface, IP, broadcast, mask, MAC, packet counters. The lo loopback interface shows 127.0.0.1 (see reserved addresses).

Modern distros deprecate ifconfig in favor of the ip suite:

ifconfig        # legacy, may need net-tools installed
ip addr         # current equivalent
man ifconfig    # man pages give syntax for any command

What you’re looking for

IP address, subnet mask, default gateway. Those three tell you the host’s subnet and its exit point.

A 169.254.x.x address means DHCP failed, not a working config.