A TXT Record provides the ability to associate some text with a domain or a sub-domain. This text is meant to strictly provide information and has no functionality as such. A TXT Record can store upto 255 characters of free form text. This Record is generally used to convey information about the zone. Multiple TXT Records are permitted but their order is not necessarily retained.
For example, you may add a TXT Record for yourdomainname.com with the value as "This is my email server". Here, if anybody was checking ALL or TXT Records of yourdomainname.com, they would notice the above text appearing in the TXT Record.
TXT Record is also used to implement the Sender Policy Framework (SPF) and DomainKeys specifications.
Sender Policy Framework (SPF):
Sender Policy Framework is an extension to the Simple Mail Transfer Protocol (SMTP). SPF allows software to identify and reject forged addresses in the SMTP MAIL FROM (Return-Path), a typical nuisance in e-mail spam.
SPF allows the owner of a domain to specify their mail sending policy, e.g. which mail servers they use to send mail from their domain. The technology requires two sides to work in tandem:
- the domain owner publishes this information in an TXT Record in the domain's DNS zone, and when someone else's email server receives a message claiming to come from that domain, then
- the receiving server can check whether the message complies with the domain's stated policy. If, for example, the message comes from an unknown server, it can be considered a fake.
DomainKeys:
DomainKeys is an email authentication system (developed at Yahoo!) designed to verify the authenticity of the email sender and the message integrity (i.e., the message was not altered during transit). The DomainKeys specification has adopted aspects of Identified Internet Mail to create an enhanced protocol called DomainKeys Identified Mail (DKIM).
There you would find 3 fields:
- Host Name: If you wish to Add a TXT Record for yourdomainname.com like yourdomainname.com, then leave the Host Name text box blank.
- Value: 255 characters of free form text can be provided in this field. This Record is generally used to convey information about the zone. For example, you may add a TXT Record for mail.yourdomainname.com with the value as "This is my email server". Here if anybody was checking ALL or TXT Records of mail.yourdomainname.com, they would notice the above text appearing in the TXT Record.
- TTL: This is the Time To Live for this Record. Any Server which once queries this Record will query it again after this time interval. The ideal TTL is 86400, which is 1 day. It can not be set to less than 14400, i.e. 4 hours.