The military tech in Halo 4 is actually one of the more interesting parts.
More UNSC Infinity facts:
The Infinity’s hull is made of 4.9 meters (16 feet) of Titanium A3 armor plating. The Infinity is also the first UNSC craft to have Covenant-style energy shielding.
The Infinity is 5.6km (3.5 miles) long, making it the largest ever UNSC craft, but still significantly shorter than the 29km Covenant Supercarrier that was destroyed by Jorge at Reach.
The Infinity carries ten Frigates - presumably these are used as landing craft.
The total crew numbers 17,151: 8,954 Naval staff, 6.021 Marines, 1,699 Intelligence staff and 477 civilians. Its passengers include Spartan IVs, ODST troopers, and UNSC Marines, Army and Air Force.
The Infinity was covertly constructed in the Oort Cloud at the very end of the Sol System in 2537, initially intended to be a last resort and base of operations should Earth be conquered or destroyed by the Covenant. Commissioned by ONI (but known to a few high-ranking UNSC officials, since it was constructed with UNSC funds) the Infinity was partly built with Hugark (Engineer) assistance and makes use of reverse-engineered Forerunner technology, particularly slipspace navigation and communication.
The Infinity has four MAC guns, 350 Archer missile pods, 250 Rapier missile pods, 500 Howler missile pods, and 830 point defence turrets.
The Infinity’s crew roster includes Master Sergeant Stacker, who has been present in every major conflict from Reach onwards - making him even more of a natural survivor than Sergeant Johnson (and equal with ODST Sergeant Buck, depending on whether he’s still alive in the Halo 4 timeline).