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Supported DNS Resource Record Types
Route 53 supports the DNS resource record types that are listed in this section. Each record type also includes
an example of how to format the Value element when you are accessing Route 53 using the API.
Note
For resource record types that include a domain name, enter a fully qualified domain name, for example, www.example.com. The trailing dot is optional; Route 53 assumes that the domain name is fully qualified. This means that Route 53 treats www.example.com (without a trailing dot) and www.example.com. (with a trailing dot) as identical.
A Format
An A record Value element must take the format of an IPv4 address in dotted decimal notation.
AAAA Format
An AAAA record Value element must take the format of an IPv6 address, in colon-separated hexadecimal format.
CNAME Format
A CNAME Value element is the same format as a domain name.
Important
The DNS protocol does not allow you to create a CNAME record for the top node of a DNS namespace, also known as the zone apex. For example, if you register the DNS name example.com, the zone apex is example.com. You cannot create a CNAME record for example.com, but you can create CNAME records for www.example.com, newproduct.example.com, and so on.
In addition, if you create a CNAME record for a subdomain, you cannot create any other resource record sets for that subdomain. For example, if you create a CNAME for www.example.com, you cannot create any other resource record sets for which the value of the Name field is www.example.com.
Route 53 also supports alias resource record sets, which allow you to route queries to an Elastic Load Balancing load balancer, an Amazon S3 bucket that is configured as a static website, or another Route 53 resource record set. Aliases are similar in some ways to the CNAME resource record type; however, you can create an alias for the zone apex. For more information, see Creating Alias Resource Record Sets.
MX Format
An MX record Value element consists of two fields: a decimal number that represents the priority of the MX record, and
the domain name of a mail host, for example, mail.example.com.
NS Format
An NS record Value element is the same format as a domain name.
PTR Format
A PTR record Value element is the same format as a domain name.
SOA Format
An SOA record Value element consists of seven fields. The first two fields are formatted as domain names and represent
the primary authority for the zone and the contact details for the zone administrator, respectively.
The remaining five fields are decimal numbers representing the zone serial number, refresh time, retry time,
expire time, and minimum time to live (TTL), respectively.
SPF Format
An SPF record Value element is the same format as a TXT format record. For information about SPF record format, refer to
the applicable documentation. For information about TXT format, see TXT Format.
SRV Format
An SRV record Value element consists of four space-separated values. The first three values are decimal numbers representing priority,
weight, and port. The fourth value is a domain name. For information about SRV record format, refer to the applicable documentation.
TXT Format
A TXT record Value element is a space separated list of double-quoted strings. A single string cannot
exceed 255 characters. In addition to the characters that are permitted unescaped in domain names,
space is allowed in TXT strings. All other octet values must be quoted in octal form. Unlike domain names,
case is preserved in character strings, meaning that Ab is not the same as aB.
You can include a literal quote in a string by escaping it.
Example
<Value>"this is a string" "a string with a \" quote in it" "a string with a \100 strange character in it"</Value>
