A set of DNS records are instructions to tell how DNS servers associate one domain to an IP address, one domain to another, or providing additional information to DNS inquiries.
Records are usually represented as a table. Each row corresponds to one record. Each record has the following four basic fields:
- Type: type of this record (what this record is about?).
- Name: the targeted domain name
- Value: what IP/domain name/information corresponds to Name?
- TTL (Time To Live): the time period a dns server should keep this record. Once expired the server has to update the record from other servers. A short TTL makes sure that once the record changes, new rule will propagate through the DNS servers fast.
Common Types of Records:
- A Record: associates a domain name to an IP address.
- CNAME Record: associates one domain to another domain
- MX Record: when an email delivery request is sent to a domain, this records routes the request to other mail server domains.
- TXT Record: specified additional information for the domain. The additional information usually has the format “