document updated 15 years ago, on May 26, 2009

Most NICs manufactured after 2004 support Auto-MDIX, which means that most of the time, you should almost never need to use a real crossover cable.

Nice features:

Only one side needs to support Auto-MDIX for it to work, both sides don't need it.
The Gigabit standard requires Auto-MDIX support, so every Gigabit NICs should support it.

Gotchyas:

Auto-MDIX is a feature that can sometimes be disabled, so you may need to enable it for a particular NIC first.
If you enable Auto-MDIX, then everything else has to be auto-negotiated too (e.g. speed, duplex). On professionally configured networks, auto-negotiation is a no-no, so Auto-MDIX shouldn't be used there except on a temporary as-needed basis.