If I enter the following two network commands:
Will BGP pick up that the 172.20.0.0 network is a /16 and that the 172.16.3.0 is a /24 or do i need to use the mask portion of this command?
The behavior of the network command varies depending on whether auto-summary is enabled or disabled. When auto-summary is enabled, it summarizes the locally originated BGP networks (network x.x.x.x) to their classful boundaries (auto-summary is enabled by default in BGP).
When auto-summary is disabled, the routes introduced locally into the BGP table are not summarized to their classful boundaries.