DNS problems when shutting down old DC/DNS server temporarily.

Environment:

2008 FFL/DFL - 3 DCs

-HOMEDC01 - 2008 SP2 - DNS, GC

-HOMEPDC -  2008 R2 SP1 - FSMO, DHCP, DNS, WINS, GC

-HOMESDC (VM) -  2016 - DNS, GC

IPV6 enabled on all per articles found online.

DC01 has been on the network for years and did everything before.  Then I brought up PDC a few years ago and transferred over all roles from DC01.  2 weeks ago I brought up SDC and set it up with DNS.  Everything looks to be in order and the plan was to demote DC01 and retire it.  I shut down DC01 for a few days and all of a sudden we started experiencing extremely slow loading times for any webpages.  I brought it back up and everything went back to normal.

I made the necessary adjustments in DHCP to only provide PDC and SDC to clients for DNS.

I ran dcdiag /test:DNS /DNSALL /e /v to see whats going on and the only thing I can see is that root hints only seem to be showing up on DC01 in the output.  I check DNS on PDC and SDC and they both have them, so not sure why they show up for only one server in the output.  Is that my problem?  What am I missing? (see attached output run from SDC, I also ran it on the other 2)

When I had DC01 off, before turning it back on, I ran nslookup and got major delays/time-outs the first time around but then would get a response eventually.  Tried clearing cache on both PDC and SDC and re-registering both.  No change.

Any direction or insight would be greatly appreciated.  TIA
DCDIAG-DNSV.txt