One of the big things that seems to trip up a lot of people when they attempt to move to Office 365 are the DNS requirements that Microsoft expects you to have in place. If you are not used to messing about with DNS the requirements can look a bit daunting. And if your present DNS provider doesn’t support the record types that Microsoft uses and/or does not make life easy for you to make the changes then the move to O365 can be pretty frustrating.
So, to make your life a bit easier, here is Rob’s O365 DNS primer (for those of you that already “get it” you should move along as there is nothing new here):
First, just what the heck IS a DNS record? Well, I’m glad you asked because there is nothing really mystical about it. In simple terms, a DNS record maps things like website names or server connections (think www.itgroove.net or mail.itgroove.net) to an IP address. DNS records are what allow systems and people to find specific resources on the Internet. You look up a name and you get the address in a similar fashion to looking up a name in a phone book or in the Yellow Pages and getting a phone number in return. Of course there are some complicated variants but the basic premise remains the same … look up something and get specific information back.
There are m any types of DNS records and each type does something specific. O365 expects you to be able to set the following types:
Microsoft lists DNS providers that work well with O365 and they also suggest, strongly, that if you have issues setting up the required records that you change DNS providers to one that is more “friendly”. I concur wholeheartedly. See my post here about painful issues with a dumb DNS provider that were resolved in about 10 minutes by changing to a DNS provider with decent tools and a modern backend. There is no reason whatsoever for your move to O365 to be blocked by DNS issues. If your provider can’t do the job, dump them. The Internet (and DNS) is ruthlessly Darwinian – the dumb provider will either “get it” or die.
Keep in mind when setting up DNS records that if your provider allows you to control the “lifetime” or the “time to live” that shorter times are better than longer. If you mess something up you want it to die off quickly so that your fixed updates take effect sooner. Also keep in mind that it can take time for your DNS updates to propagate across the web. If you are able to control where you QUERY external DNS (lookup) then I suggest you point at Google’s DNS servers – 126.96.36.199 and 188.8.131.52 – because they update incredibly fast. I’ve seen Google catch DNS changes made at a DNS provider inside of 30 seconds from the point the DNS provider accepted the DNS change. It’s a great way to see if your changes are what you want. Also, the DNS test inside O365 will pick up the changes fairly quickly and once you get past the DNS test you are away to the races in terms of your O365 tenancy.
I hope this helps clarify O365’s DNS requirements a little bit.