ipconfig

In short: A Windows command that shows the IP configuration of the network cards and manages DHCP addresses and the DNS cache.

In more detail: ipconfig shows the IP address, subnet mask and default gateway of each network card. It is usually the first command when a network fault occurs. On Linux the equivalent is ip addr, formerly ifconfig.

In Depth

The most important calls

Call	Effect
ipconfig	short overview per network card
ipconfig /all	all details: MAC address, [[dhcp
ipconfig /release	returns the address received from the DHCP server
ipconfig /renew	requests a new address (DORA sequence)
ipconfig /flushdns	clears the DNS cache
ipconfig /displaydns	shows the DNS cache

Example output

Ethernet adapter Ethernet:
   IPv4 Address. . . . . . . . . . . : 192.168.1.23
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1

How to read the output

• Home-network address (192.168.x.x, 10.x.x.x, 172.16-31.x.x): Everything is fine, the address comes from the router.
• 169.254.x.x: Automatic fallback address (APIPA). The computer found no DHCP server; check cable, Wi-Fi or router.
• Empty default gateway: There is no way to the internet.
• Adapter “Media disconnected”: No cable or no Wi-Fi connection.

Typical uses

After a router change ipconfig /release and /renew, for outdated DNS entries /flushdns, for support calls copy /all (think beforehand whether you want to share the MAC address and IP addresses).

See also: Network Commands in the CMD, DHCP, IP Addresses, Subnet Mask, DNS, CMD, Ping