Working with your network settings – two sets of commands
For most of the Linux lifespan that people are familiar with, ifconfig (interface config) and related commands have been a mainstay of the Linux operating system, so much so that now that it's deprecated in most distributions, it still rolls off the fingers of many system and network administrators.
Why were these old network commands replaced? There are several reasons. Some new hardware (in particular, InfiniBand network adapters) are not well supported by the old commands. In addition, as the Linux kernel has changed over the years, the operation of the old commands has become less and less consistent over time, but pressure around backward compatibility made resolving this difficult.
The old commands are in the net-tools software package, and the new commands are in the iproute2 software package. New administrators should focus on the new commands, but familiarity with the old commands is still a good thing...