ipconfig - Windows Command Line Utility

How and When to Use ipconfig in Windows

WIndows 10 desktop running ipconfig in Command console

In Windows, ipconfig is a console application designed to run from the Windows command prompt. This utility allows you to get the IP address information of a Windows computer. It also allows some control over active TCP/IP connections. ipconfig replaced the older winipcfg utility.

Using ipconfig

From the command prompt, type ipconfig to run the utility with default options. The output of the default command contains the IP address, network mask, and gateway for all physical and virtual network adapters.

ipconfig supports several command line options. The command ipconfig /? displays the set of available options.

ipconfig /all

This option displays the same IP addressing information for each adapter as the default option. Additionally, it displays DNS and WINS settings for each adapter.

ipconfig /release

This option terminates any active TCP/IP connections on all network adapters and releases those IP addresses for use by other applications. pconfig/release can be used with specific Windows connection names. In this case, the command affects only the specified connections, not all connections. The command accepts either full connection names or wildcard names. Examples:

ipconfig /release "Local Area Connection 1"
ipconfig /release *Local*

ipconfig /renew

This option re-establishes TCP/IP connections on all network adapters. As with the release option, ipconfig /renew takes an optional connection name specifier.

Both /renew and /release options only work on clients configured for dynamic (DHCP) addressing.

Note: The remaining options are only available on Windows 2000 and newer versions of Windows.

ipconfig /showclassid, ipconfig /setclassid

These options manage DHCP class identifiers. DHCP classes can be defined by administrators on a DHCP server to apply different network settings to different types of clients. This is an advanced feature of DHCP typically used in business networks, not home networks.

ipconfig /displaydns, ipconfig /flushdns

These options access a local DNS cache that Windows maintains. The /displaydns option prints the contents of the cache, and the /flushdns option erases the contents.

This DNS cache contains a list of remote server names and the IP addresses (if any) they correspond to. Entries in this cache come from DNS lookups that happen when attempting to visit websites, named FTP servers, and other remote hosts. Windows uses this cache to improve the performance of browsers and web-based applications.

In home networking, these DNS options are sometimes useful for advanced troubleshooting. If the information in your DNS cache becomes corrupted or outdated, you could face difficulty accessing certain sites on the internet. Consider these two scenarios:

  • The IP address of a website, email server or other server changes (a rare occurrence). The name and address of this site normally stay in your cache for 24 hours after your last visit. You may need to clear the cache to access the server sooner.
  • A website or other server was offline when you last visited it (a rare occurrence) but has since has come back online. The cache normally keeps a record that the server is offline for five minutes after your last visit. You may need to clear your cache to access the server sooner.

ipconfig /registerdns

This option updates DNS settings on a Windows computer. Instead of merely accessing the local DNS cache, however, this option initiates communication with both the DNS server and the DHCP server to re-register with them.

This option is useful in troubleshooting problems involving a connection with the internet service provider, such as failure to obtain a dynamic IP address or failure to connect to the ISP DNS server.​​

Like the /release and /renew options, /registerdns optionally takes the name(s) of specific adapters to update. If no name parameter is specified, /registerdns updates all adapters.

ipconfig vs. winipcfg

Prior to Windows 2000, Microsoft Windows supported a utility called winipcfg instead of ipconfig. Compared to ipconfig, winipcfg provided similar IP address information but through a primitive graphical user interface rather than the command line.