Recently, we promoted Server 2016 DC's (Domain Controllers) from Server 2012R2 machines. All FSMO roles have been successfully migrated over to the 2016 server(s) and the primary 2016 DC has the schema. I ran a dcdiag on the new DC and received no errors but, for some reason when I change the IP's from the old DC's (Both primary and secondary) to the new ones, access to Internet sites take anywhere from 20 secs to getting a page cannot be displayed. Everything else, works in the domain. Email, file share access, printing, etc. The only issue is the delay to the Internet. The only thing I haven't done was to rename the new servers with the old servers' names. I had to migrate the IP's because there are way too many back end configs throughout the network that point to those IP's.
Any clue on what may be causing the delay in Internet access? I'm thinking maybe a DNS issue. I just don't know where since DNS shows all 4 servers in its zone(s).