Updating zone file serial number convention
If the record points to an EXTERNAL server (not defined in this zone) it MUST be a FQDN and end with a '.' (dot), for example, ns1.If the name server is within this domain (in this zone file) it can be written as ns1 (without the dot) which will be expanded to include the $ORIGIN.When configuring BIND, all times are specified in seconds. However, it is possible to use abbreviations when specifying units of time other than seconds, such as minutes ( Seen individually, directives and resource records can be difficult to grasp. ( 2001062501 ; serial 21600 ; refresh after 6 hours 3600 ; retry after 1 hour 604800 ; expire after 1 week 86400 ) ; minimum TTL of 1 day IN NS dns1. directive is a numerical value used by slave servers to determine the length of time to wait before issuing a refresh request in the event that the master nameserver is not answering. ( 2001062501 ; serial 21600 ; refresh after 6 hours 3600 ; retry after 1 hour 604800 ; expire after 1 week 86400 ) ; minimum TTL of 1 day 1 IN PTR dns1. If the master has not replied to a refresh request before the amount of time specified in the directive is the amount of time other nameservers cache the zone's information. dns1 IN A 10.0.1.1 dns2 IN A 10.0.1.2 server1 IN A 10.0.1.5 server2 IN A 10.0.1.6 ftp IN A 10.0.1.3 IN A 10.0.1.4 mail IN CNAME server1 mail2 IN CNAME server2 www IN CNAME server1$ORIGIN 1.0.10.
The SOA resource record is an essential part of the DNS zone file, it indicates the basic properties of the domain name server and the zone that the domain is in.
In BIND implementations this is defined to be a 10 digit field.
This value MUST increment when any resource record in the zone file is updated.
NOTE: Format is mailbox-name.domain.com, for example, hostmaster.(uses a dot not the more normal @ sign, since @ has other uses in the zone file) but mail is sent to [email protected]
Most commonly ending with a '.' (dot) but if the email address lies within this domain you can just use hostmaster (see also example below). Unsigned 32 bit value in range 1 to 4294967295 with a maximum increment of 2147483647.