Manage DNS records in Azure DNS

Manage DNS records in Azure DNS

Each record in the domain name system includes the following properties:

• Name The name of the DNS record is combined with the name of the DNS zone to form the fully qualified domain name (FQDN). For example, the record “www” in zone “contoso.com” corresponds to the FQDN “www.contoso.com.”
  • Type The type of DNS record determines what data is associated with the record and what purpose it is used for. A list of record types supported by Azure DNS is provided in Table 4-7.
  • TTL The Time-to-Live (TTL) property tells recursive DNS servers how long a DNS record should be cached.
  • RDATA The data returned for each DNS record. The type of data returned depends on the DNS record type. For example, an A record will return an IPv4 address, whereas a CNAME record returns another domain name.

The collection of records in a DNS zone with the same name and the same type is called a resource record set. (These collections are also referred to as “RRSets” and as “record sets” in Azure DNS). Records in Azure DNS are managed using record sets. Record sets are a child resource of the DNS zone and can contain up to 20 individual DNS records. The name, type, and TTL are config- ured on the record set, and the RDATA is configured on each DNS record within the record set.

To create a DNS record set at the root (or apex) of a DNS zone, use the record set name @. For example, the record set named @ in the contoso.com zone will resolve against queries for “contoso.com.” You can also use an asterisk (*) in the record set name to create wildcard records (subject to DNS wildcard matching rules).

Azure DNS supports all commonly used DNS record types. The full list of supported record types—together with a description of each—is provided in Table 4-7.

TABLE 4-7 DNS record types in Azure DNS

DNS Record Type	Remarks
A	Used to map a name to an IPv4 address.
AAAA	Used to map a name to an IPv6 address.
CAA	Used to specify which certificate authorities can issue certificates for a domain. Note that CAA records are not currently available in the Azure portal, so they must be configured using the Azure CLI or Azure PowerShell.

DNS Record Type	Remarks
CNAME	Provides a mapping from one DNS name to another. The DNS standards do not allow CNAME records at the zone apex. In addition, you cannot create a CNAME record with the same name as a record of any other record type, and CNAME record sets only support a single DNS record rather than a list of records. These are DNS RFC constraints, not Azure DNS limitations.
MX	Used for mail server configuration.
NS	An NS record set at the zone apex containing the name servers for the DNS zone is required by the DNS standards. This is created for you when the DNS zone is created. It can be edited, for example to add additional records when co-hosting a DNS zone with more than one provider, but not deleted. You can create additional NS record sets to delegate child zones.
PTR	Used for reverse DNS lookups in reverse lookup zones.
SOA	An SOA record is required at the apex of every zone. This is created and deleted with the DNS zone resource.
SRV	SRV records are used for service discovery for a wide range of services, from Kerberos to Minecraft to the Session Initiation Protocol used for internet telephony. Note that the Service and Protocol parameters are specified as part of the record set name, such as _service._protocol.media.contoso.com. Some DNS services prompt you to enter these values separately and then merge them to form the record set name. With Azure DNS, you need to specify them as part of the record set name, but they are not entered separately.
TXT	Used for a wide range of applications, including email Sender Policy Framework (SPF).