Upon setting up my zone files, I went back to review my TTL values. The default is set for 24 hours and I have individual TTL values set for each individual record.
My thought was NS, MX, and CNAME records should have a higher TTL value because they likely will not change often. Somewhere along the lines of 1wk seems appropriate and will offer less load on the server. The A records however, can have a lower value, lets say 12hrs.
My question is, if MX record
mx1.example.com has a TTL of 1wk and
mx1.example.com has A record of
a.b.c.d which has a TTL of 12hrs, won't the client still query the DNS server every 12 hours to make sure the A record is current? Since DNS queries are minimal, is it worth having higher TTL values for NS, MX, and CNAME at that point?