List of external systems connecting to SAP

Hi All,

Can anybody let me know where I need to look for the list of all the external systems connected to SAP.

Actually we need to collect DNS aliases for the APPS migration to a new data center.

Is there a way to find out some sort of a list of external systems they connect to within SAP?

Also any special info concerning naming standards would be helpful.

Also, At some point a testing plan will need to be developed to ensure the necessary testing has been done to verify the applications work as expected and are communicating in our new network. REMEMBER we are NOT introducing new functionality, rather we are taking our existing applications currently from one data center and migrating the Prod clients to the new Data center.

Any thought and comments would be helpful in our planning for a successful implementation......

Am not sure that this question relevant to ABAP only, should I need to ask this question to a different area other than ABAP?