The AK-74 is a moderately powerful assault rifle which will kill a zombie in two body shots. It can be found in all military loot spawns. Also available are the AKS-74 Kobra, which is identical, except it has a very useful Kobra green dot sight, and the AKS-74U, which has a shorter barrel and a slightly shorter effective range.
This page contains information about the mod version of DayZ. Standalone information is available here.