Reg: TTL & Refresh

[Durai]

Hi All,
I am new to DNS.

I am having file with like following content:

@   IN  SOA     nameserver.place.dom.  postmaster.place.dom. (
                               1            ; serial number
                               3600         ; refresh   [1h]
                               600          ; retry     [10m]
                               86400        ; expire    [1d]
                               3600 )       ; min TTL   [1h]

My doubt is, I am having the zone files as master. When the TTL time & refresh expires, What will happen?

My guess is, If the zone files are "slave files" means Zone transfer will occur with matching serial number. But mine is the master file.


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