The Viper 2 is a ship typically seen in the Police forces of many systems across human space - not only Alliance, but Imperial and Federation space too. It is specifically designed as a police craft. It is therefore not surprising that this ship is used as the AJN military police force's patrol craft.
That's not all that it's used for though. It is also used as a light attack fighter by several AIS members. Since it is designed for short range patrolling and defence, this is the use the naval units put it to - rear-guard defence patrols and interdiction. It is also equipped to be carried by the Victor class battlecruiser for deep space patrols (usually to protect the cruiser). The Viper 2 is built under license in many Alliance systems, and local systems tend to have their own agreements with local shipyards to construct this vessel to AJN specifications.
The current variants are:
There are only minor differences between the F.1 and F.3 (neither of which are hyperspace equipped). The F.1 has a standard 1MW beam laser, the F.3 has the more expensive new-technology, 560 n.m. wavelength dual beam 2.5MW beam laser. Both versions are equipped to carry up to four standard NN-550 missiles.