Ipconfig May Not Show Complete IP Configuration for an Adapter

The Ipconfig tool may intermittently not display complete Internet Protocol (IP) information for a network adapter that is configured to obtain IP configuration information from a Dynamic Host Configuration Protocol (DHCP) server. Instead, Ipconfig may intermittently display all zeros for the IP address and subnet mask, and display no default gateway. Or, Ipconfig may display the correct IP address and subnet mask but no default gateway.

This behavior can occur on media-sense-capable network adapters. If the adapter's network cable is disconnected, a Network Cable Unplugged icon appears on the taskbar and the adapter sends a media-sense event to the IP stack. At this point, Ipconfig reports: "Media State...: Cable Disconnected."

When the cable is reconnected and the Network Cable Unplugged icon disappears from the taskbar, the adapter sends another media-sense event to the IP stack. The IP stack then starts an adapter initialization and configuration process.

When initialization on the adapter begins, Ipconfig reports all zeros for the IP address and subnet mask, and no default gateway.

After the adapter is initialized, it begins the process of obtaining its IP configuration from the DHCP server. After it receives a DHCP offer, it attempts to perform a conflict detection process to determine whether another computer is already using the offered IP address. At this point, approximately three seconds after the Network Cable Unplugged icon disappears from the taskbar, Ipconfig shows the IP address and subnet mask, but no default gateway.

Approximately two seconds later, when the validity of the DHCP lease has been verified, Ipconfig shows the correct IP address, subnet mask, and default gateway.

This behavior is by design.