When do его, её, and их begin with н?

I read in The New Penguin Russian Course that его, её, and их begin with н when they follow a preposition. But Rosetta Stone shows them beginning with н even when they are not following a preposition. Is Rosetta Stone correct when they do this?

http://content.screencast.com/users/...4/00000017.png

And what do you think "У" is if not a preposition? :)

Read your previous topic again:
viewtopic.php?f=3&t=16865&p=206490#p206490

Quote:

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"Него", "неё", "них", "ними", etc. are used as a case form (not a sign of possession) mainly in two situations:
1) after simple prepositions: без, в, для, до, за, из, к, на, над, о, от, по, под, перед, при, про, с, у, через;
[...]

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Thanks to everyone for setting me straight. I forgot what у was, obviously. I was thinking of it more like 'have' instead of 'at'. Doh!

Do Его собака and У него собака mean the same thing?

Quote:

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Originally Posted by SoftPretzel

Do Его собака and У него собака mean the same thing?

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No.
его собака = his dog
у него собака = he has a dog