I've never made a change to a DNS record before. In researching the DNS servers I inherited (Solaris 5.6 with BIND v9.2.3), I found that DNS_A (private) is the primary DNS server and it replicates to DNS_B and DNC_C (both public) via the zone's db file option:
allow-transfer { 192.in.ter.nal; 173.ex.ter.nal; };
The header from the zone file is:
@ IN SOA DNS_A.redacted.com. postmaster.redacted.com. (
2013010401 ; serial
300 ; refresh
120 ; retry
6048000 ; expire
300 ) ; ttl
I understand that I have to increment the serial number when I make the change so that the secondary DNS servers recognize a change, but will my secondary DNS servers not look for a change until the "expire" time is reached? If that's specified in seconds, that's 70 days.
What do the refresh
, retry
, expire
, and ttl
times mean?
Best Answer
You have to change the serial value to send a notification to all your slave servers telling them that the zone just changed so they can get the update.
Here follows the meaning of these items:
More on: http://www.zytrax.com/books/dns/ch8/soa.html