Updating zone file serial number convention simplified dating
This is the length of time, in seconds, that a zone resource record is valid. Each resource record can contain its own TTL value, which overrides this directive. 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. The SOA defines the global parameters for the zone (domain). A Slave DNS does not use this TTL value but various parameters defined within the SOA RR - see below. Any name server that will respond authoritatively for the domain.Only one SOA resource record (RR) is allowed in a zone file and it must be the first RR in the zone. ( 2003080800 ; sn = serial number 172800 ; ref = refresh = 2d 900 ; ret = update retry = 15m 1209600 ; ex = expiry = 2w 3600 ; nx = nxdomain ttl = 1h ) ; the following are also valid using @ and blank @ IN SOA ns. Called the Primary Master in the context of Dynamic DNS (DDNS).
The convention is to use a date based sn value to simplify the task of incrementing the sn - the most popular convention being yyyymmddss where yyyy = year, mm = month and dd = day ss = a sequence number in case you update it more than once in the day!
All directives and resource records should be entered on individual lines.
Comments can be placed after semicolon characters ( Sets the default Time to Live (TTL) value for the zone.
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.