DNS Resource Records
A Resource Record (RR) contains a specific information about the domain. Some common ones are A record which contains the IP address of the domain, AAAA record which holds the IPv6 information, and MX record which has mail servers of a domain.
An A record is used as the primary method of connecting a hostname to an IP address. A records point to IPv4 addresses. An A record will look like this in a zone file.
@ 5m IN A 18.104.22.168 blog 5m IN A 22.214.171.124 blog.example.com. 5m IN A 126.96.36.199
An AAAA record is just like an A record but points to IPv6 addresses instead of IPv4 address.
@ 5m IN AAAA 2607:f8b0:4009:812::200e blog 5m IN AAAA 2607:f8b0:4009:812::200e blog.example.com. 5m IN AAAA 2607:f8b0:4009:812::200e
CNAME records are aliases to an A or AAAA record (or both). They point a hostname to an already defined record.
www 5m IN CNAME example.com.
The SOA (Start of Authority) records are used to determine how your zone propagates to the secondary nameservers.
1 2 3 4 5 6 7 |--------------| |----------------| |--------| |---| |--| |----| |-| ns1.example.com. admin.example.com. 2017021100 86400 7200 604800 300
- The primary DNS server (
- The email address (with the
@replaced with a
.) of the person responsible for the domain (
- A timestamp that changes whenever you update your domain in the format
##is the number of times the zone has been updated today (
- The number of seconds before the zone should be refreshed (
- The number of seconds before a failed refresh should be retried (
- The upper limit in seconds before a zone is considered no longer authoritative (
- The negative result TTL (for example, how long a resolver should consider a negative result for a subdomain to be valid before retrying) (