Google uses ~40 Class C IP blocks.
I summise elsewhere that each Class C block is a bank of perhaps 10 000 servers in a room.
There is a pattern to the IP address usage. The IPs always end in .44, .99, .104, .107, .143 and so on. There are about 30 for each block.
There are also several aliases that can be used, and they give different results again.
These include the GFE name, like gfe-eh.google.com where "eh" is one of ~40 two-letter pairs. These letters have a direct association with the Class C block used. There is also "gfe-xx2" for most of them, and "gfe-xx3" for many of them, and "gfe-xx4" for a very few of them.
The alternative designators come in the form eh-in-f99.google.com where the "eh" is the same two-letter pair as before, and the "99" is the last digits in the IP address. So, there are about 30 of those active, for each of the ~40 two-letter pairs.
There's a list of all the blocks, printed about a year ago in this forum. There have been a few changes since then, but 90% of it is still OK.