Which of the following verification tasks should the network administrator perform NEXT?

A company just migrated its email service to a cloud solution. After the migration, two-thirds of the internal users were able to connect to their mailboxes, but the connection fails for the other one-third of internal users. Users working externally are not reporting any issues.

The network administrator identifies the following output collected from an internal host:

c:user> nslookup newmail.company.com

Non-Authoritative answer:

Name: newmail.company.com

IPs: 3.219.13.186, 64.58.225.184, 184.168.131.243

Which of the following verification tasks should the network administrator perform NEXT?
A . Check the firewall ACL to verify all required IP addresses are included.
B . Verify the required router PAT rules are properly configured.
C . Confirm the internal DNS server is replying to requests for the cloud solution.
D . Validate the cloud console to determine whether there are unlicensed requests.