I would like to do the incremental migration, but am not sure about the part in the instructions about DNS as this part of the instructions seems a bit incomplete ... i have set the ttl to 300 (NOTE that most servers on the web will probably ignore this setting and cache for at least 1h anyhow ) for all my domains but not sure what to set for MX records in my DNS server
FYI source server will be mx1.myserver.ca and destination server will be mx2.myserver.ca
i now have the following records on the mail server for source and destination machines
mx1.myserver.ca. IN A x.x.x.131
mx2.myserver.ca. IN A x.x.x.132
and these on each of the domains that need to be transfered
somedomain.com. IN MX 22 mx1.myserver.ca.
somedomain.com. IN MX 100 mx2.myserver.ca
however there is no mention in any doc that i can find about what/how to setup DNS records or if a backup MX isa plausible way to do migration without down time? as usual i am probably missing something obvious here and may not need or want backup MX records
please advise! and thank you in advance