Hello Thom,
Thank you for contacting us. Please see my answers below:
-Can you let me know if a restart of the Delphix engine is required?
No, A restart of the Delphix engine is not required.
-Do we need to stop any VDB's etc?
The VDB's will not need stopping, This will not affect the VDB's.
-Does the version of Delphix have any impact?
I have personally tested this operation as far back as version 3.2.4.2 and not encounted any problems. (If you're on this version or older then I would recommend updated your Engine to the latest.)
Please ensure that the new DNS server can resolve the environments associated with the Delphix engine.
If you have any further questions please let me know.
Adam.