I have seen lot of MP issues where MPCERT and MP Policy tests are working fine. However, MP list is giving errors.
Name resolution should work without any issues if you want a stable and reliable system.
Check whether DNS server is reachable or not.
1) Try NSLOOKUP
DNS request timed out.
timeout was 2 seconds.
Default Server: UnKnown
(2)Try pinging the DNS server
Ping request could not find host . Please check the name and try again.
Refer to the valid DNS server and put the details in the DNS entry of SCCM site server.
The best practice would be to keep more than one DNS server entry in the configuration.