Domain name transfers between registrars

Hi, all!  I'm looking for some specific answers on downtime and/or what's transferred when during a domain transfer from one registrar to another.  Some posts/threads have suggested it only takes "a little while" and transfers the entire zone file, and others have suggested it does *not* transfer the zone file and Network Solutions own documentation says "5-7 days" after administrative approval.  So here's the situation...

We're in the process of a merger with another company, with Registrar-A.  They are running their own Exchange system (MX records) and website (WWW record), amongst others.  Over a very short time period (one weekend) we need to essentially change their WWW and MX records to point to our smarthost (Mimecast) for our domain, at Registrar-B.

First, I don't know how long the current solutions provider will keep the domain registration alive at Registrar-A, so do I need to do the domain transfer FIRST, hope nothing changes on Registrar-A, and change the zone records (NS & MX records) on Registrar-B on the Big Day?

Second, my concern is that doing a domain transfer before the Big Day will either stop the registrar from hosting the record at their whim (several posts have seen this done in the past), and whether creating a new Zone file on Registrar-B will screw up the zone file/hosting at Registrar-A.

Website records aren't relevent; the key here is zero downtime when we change the MX record to have mail start flowing into our smarthost @ Mimecast (for

It's been a few years since I've done this with an active domain, so I need to be sure that all the I's are dotted and the T's are crossed.  Thanks!
Steve BottomsSr Network AdminAsked:
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Tony GiangrecoCommented:
That period of downtime is dependent upon how long it takes for the zone servers to replicate (all sync up with the same updates). I've worked with Godaddy, Network Solutions and a few others. Normally if everything on new new side is setup and ready to receive mail, it still takes about 24 to 48 hours. Most registrars send the updates out twice a day which starts the update process. You might try finding out what registrars you will be dealing with and make sure your changes are completed before that release time.

There are variables you will be working with. Just contact both registrars ahead of time to get the most accurate info as son as possible,

Hope this helps!

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