What are some lenses that work great with portraits? (Nikon)?

What are some good lenses that work well with a Nikon D5100 and take good portraits? I know the prime lenses are good, but what about zoom lenses?

Two really.

* The nifty fifty Nikkor AF-S 50 mm f/1.8 or f/1.4
* The Nikkor AF-S 24-70 mm f2.8

I'd only use a zoom if you're taking candid portraits

Most portrait photographers rely on an 85mm prime as their go to lens. On a Nikon D5100 with a magnification factor of 1.5x the 50mm f/1.8 lens will actually be a 75mm lens which is quite close to the 85mm. Here is a link to see it on Amazon… Http://amzn.to/10RpvQU
It won't break the bank either as it just over $100:-)

If money is not object I would look at the Tamron 70-200 f/2.8 zoom lens. This is probably the most widely used lens by wedding and portrait photographers. Truth be told, the Nikon version is a better lens, but is almost double in price. Here is a link to check out the lens on Amazon… Http://amzn.to/1nu6sdp

I hope this info helps you to make a decision on which lens to purchase.
Happy Shooting:-)