Updating mx records in the dns
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The characteristic payload information of an MX record is the fully qualified domain name of a mail host and a preference value.
Note: Typically it takes about 15 minutes for DNS changes to take effect.
However, it can occasionally take longer for a change you've made to update across the Internet's DNS system.
Basically, the facility where the mail server is will be changing its IP pool and this forces me to have to change the A and MX record for the mail server.
Since I am not changing the DNS server itself (not moving the records to a different authoritative server), will the change be near instantaneous or will it still take up to 48 hours because of caching on different non authoritative DNS servers that may have queried recently?
(The people running these systems need to die in a fire, and if I ever get elected Grand overlord of The Internet, they will).