What is a TXT record?
TXT records are designed to contain generic text or other information for your domain name. They can also be used to provide SPFs (email authentication) or domain ownership confirmations for Google or other providers.
Please note that the value of a TXT record is limited to 255 characters. If you have a longer record (DKIM for example), you'll need to "split" this record into two 255-character strings defined by quotation marks, with no space between each string. Your record should look like this:
@ 1800 IN TXT "first string of 255 characters""second string of 255 characters""possibly third string of 255 characters"
Note
BIND syntax (the "language of DNS") requires that all TXT records on the same domain/subdomain have the same TTL.
Here are a few examples:
@ 10800 IN TXT "what you want to add as text as required"
for a subdomain
something 10800 IN TXT "insert your information here".
(you'll replace "something" in the example above with the chosen subdomain. The most common is "www").