TXT record
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| Internet protocol suite |
|---|
| Application layer |
| Transport layer |
| Internet layer |
| Link layer |
A TXT record (short for text record) is a type of resource record in the Domain Name System (DNS) used to provide the ability to associate some arbitrary and unformatted text with a host or other name, such as human readable information about a server, network, data center, and other accounting information.[1] A domain is not limited to having only one text record, any fully qualified domain may potentially have several records.
Common uses include defining to verify domain ownership or in setting up Sender Policy Framework,[2] DomainKeys, and DomainKeys Identified Mail records which are used to validate legitimate email sources from a domain.[3]
Format
To store new types of information, the experimental RFC 1464 suggests a structured format in TXT data fields. The format consists of the attribute name followed by the value of the attribute. The name and value are separated by an equals sign (=).
The general syntax is:
<owner> <class> <ttl> TXT "<attribute name>=<attribute value>"
Example:
name ttl class rr text joe IN TXT "Located in a black hole"
- Name: This will be the host for your domain which is actually a computer within your domain. Your domain name is automatically appended to your name. If you are trying to make a record for the system www.example.com, then all you enter in the textbox for the name value is "www".
Note: If you leave the name field blank it will default to be the record for your base domain. The record for your base domain is called the root record or apex record. - Value: Free form text data of any type. May be no longer than 255 characters. Each word will be treated as a separate string unless one or more strings is enclosed in quotes.
- TTL: The TTL (Time to Live) is the amount of time your record will stay in cache on systems requesting your record (resolving nameservers, browsers, etc.). The TTL is set in seconds, so 60 is one minute, 1800 is 30 minutes, etc..
Systems that have a static IP address should usually have a TTL of 1800 or higher. Systems that have a dynamic IP address should usually have a TTL of 1800 or less. The lower the TTL the more often a client will need to query the name servers for your host’s (record’s) IP address this will result in higher query traffic for your domain name. However, a very high TTL can cause downtime if you need to switch your IP addresses quickly.
Attribute name matching rules
The attribute name is considered case-insensitive.
During lookups, TXT records that do not contain an unquoted "=" are ignored. TXT records that seem to contain a null attribute name, that is, the TXT-DATA starts with the character "=", are also ignored.
Leading and trailing whitespace (spaces and tabs) in the attribute name are ignored unless they are quoted (with a "`").
Note that most DNS server implementations require a backslash (\) or double quote (") in a text string to be quoted with a preceding backslash. Accent grave ("`") was chosen as a quoting character in this syntax to avoid confusion with "\" (and remove the need for confusing strings that include sequences like "\\\\").
Attribute values
All printable ASCII characters are permitted in the attribute value. No characters need to be quoted with a "`". In other words, the first unquoted equals sign in the TXT record is the name/value delimiter. All subsequent characters are part of the value.
See also
- Author Domain Signing Practices
- Domain-based Message Authentication, Reporting and Conformance (DMARC)
- DomainKeys Identified Mail (DKIM)
- E-mail authentication
- List of DNS record types
References
- ^ Rich Rosenbaum (1993). RFC 1464 Using the Domain Name System To Store Arbitrary String Attributes. IETF. doi:10.17487/RFC1464. RFC 1464. Retrieved 5 February 2016.
{{citation}}: Unknown parameter|month=ignored (help) - ^ Scott Kitterman (2014). "DNS Resource Records". Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1. IETF. sec. 3.1. doi:10.17487/RFC7208. RFC 7208. Retrieved 26 April 2014.
{{citation}}: Unknown parameter|month=ignored (help) - ^ "About TXT records". Google Apps Administration. Google. Retrieved 17 August 2014.