Lookup data from one column, replace found data in from another..

Hi All,

Have been searching for something to deal with this which I am sure is really simple, but I can't get my head around it.

I have two sheets:

Data
Lookup

In Data is a list of IP addresses in two columns...source and destination.

For both columns, i'd like the IP addresses to be replaced with the corresponding name in the Lookup sheet.

See the attached as an example...I've included a sheet which shows what I expect to be returned.

I'm sure its a simple Vlookup or something but not sure how that works if you want it to replace the contents of the original cell.. Or would it need to go into a new worksheet?

Hope someone can help!