Before performing a DNS change, it is common practice to lower the TTL from it's regular value (a day or more, typically) down to something really small, like 5 minutes.
Complicating this procedure is the fact that some badly-behaved dns caching resolvers ignore the specified TTL and substitute their own values.
Question: What is the proper address to list for mx for on my internal DNS servers.
Should I use the real external IP (which might cause a NAT issue) or the internal IP of my Exchange server? Are the potential problems with internal and external MX addresses not matching?
Contributors: Check the Domains FAQ if you don't find what you're looking for. Get support.) After you add these records at Google Domains, your domain will be set up to work with Office 365 services.