Best path in BGP Routing Assuming 'Network A' is having 2 ISPs which are directly connected to 'Network B', which path will be used to connect to 'Network B'? Network A --> IP Transit A / IP Transit B --> Network B

BGP has a long list of checks to determine which path is "best". The algorithm goes through the list from top to bottom, and stops as soon as a difference is found.

You can find a good description of this list at Cisco and Juniper (and probably on many more locations and books), including advise on how to manipulate the path selection.

In your case, the tie breakers (in order) will probably be:

* Prefer the path with higher local preference.
* Prefer the path with the shortest autonomous system (AS) path value.
* Prefer the path that was received first (the oldest one).
* Prefer the path that comes from the BGP router with the lowest router ID.