My infrastructure is WS 2012 R2 Standard with AD services installed as a main server. There's a VW server running on it with EXCHG 2013 running on it.
The EXCHG has been unstable in sending and receiving emails from outside due to DNS issues. Sometimes when I troubleshoot I can browse internet from the VM sometimes not. The errors I see in the EXCHG is DNS resolution issues. The forwarders on the DNS server are correct - my ISP Cox ones. I tyrend adding and removing the root hits with no success. I added 8.8.8.8 and 8.8.4.4 it helped for a while then I again got issues, deleted them it resolved issued and again I got them. It seems like interminient issue with DNS. No antivirus or anything running on VM that could block ports. Please suggest!