Continuous DNS Lookup

In our environment, Appian Cloud and our internal Business Database(not Appian's default Database) talk over VPN tunnel.

DNS Lookup is happening for every 7.5 Minutes for our Data Sources(which are configured in Admin page).

This should be happening only when Appian makes a call to our internal Business Database.

Is this because of the resource pooling for Database connections?

Weird part is DNS Lookup is even happening for our old Data Source.

We recently updated our Data Source to connect to a new migrated Database.

Let's say we were connecting to a Data Source 'A' before. We have recently migrated from 'A' to 'B' and so we updated the Data Source to point to B in Admin page.

DNS Lookup is now happening for both A and B, resulting a call to the old Database A which should not be happening.

Does anyone seen this behavior before? What might be causing this?

Please share your thoughts.

Thank you!