DNS (Zones and Records)/Mechanism of DNS Lookup
puchi-engineerDNS (zones and records)
Each node manages data called a DNS zone, which is name resolution information about its own domain.
The unit of data contained in a zone is called a "record", and there are types as shown in the table below. Records handle not only the information on the correspondence between host names and IP addresses, but also various information such as host name aliases.
Specify the zone information as follows.
● Zone information
$TTL 86400
@ IN SOA dns.company.co.jp. postmaster.company.co.jp. (
20091218001 ; Serial
10800 ; Refresh
3600 ; Retry
604800 ; Expire
3600 ) ; Negative cache TTL
IN NS dns.company.co.jp.
IN NS dns2.company.co.jp.
IN MX 10 dns.company.co.jp.
IN MX 20 mail.company.co.jp.
localhost IN A 127.0.0.1
dns IN A 192.168.1.1
dns2 IN A 192.168.1.2
mail IN A 192.168.1.3
sv01 IN CNAME dns
sv02 IN CNAME dns2
sv03 IN CNAME mail
The record types are as follows.
| Record type | Definition example / Meaning |
| SOA | example) @ IN SOA dns.company.co.jp. postmaster.company.co.jp. 20091218001 ; Serial 10800 ; Refresh 3600 ; 604800 ; Expire 3600 ) ; Negative cache TTL |