I have a two sheets of data..

Sheet 1
A B C
1. Names Sites Networks
2. name1 site1 ?
3. name2 site1 ?
4. name3 site2 ?
5. name4 site3 ?

Sheet 2
A B
1. Networks Sites
2. network1 site1
3. network1 site2
4. network2 site3
5.network3 site4

I would like to use the info on Sheet 2 to fill in the empty column of networks on Sheet 1.
Any/all help is appreciated!