{"id":27991,"date":"2026-03-04T19:45:43","date_gmt":"2026-03-04T17:45:43","guid":{"rendered":"https:\/\/www.cheops-technology.ch\/docs\/what-is-the-format-of-dns-resource-records\/"},"modified":"2026-03-05T12:58:48","modified_gmt":"2026-03-05T10:58:48","password":"","slug":"what-is-the-format-of-dns-resource-records","status":"publish","type":"docs","link":"https:\/\/www.cheops-technology.ch\/en\/docs\/what-is-the-format-of-dns-resource-records\/","title":{"rendered":"What is the format of DNS resource records?"},"content":{"rendered":"\n

All resource records have a defined format that uses the same first-level fields, as described in the following table.<\/p>\n\n

A<\/h2>\n\n
Description:<\/strong> A resource record (host address). Maps a DNS domain name to a 32-bit Internet Protocol (IP) version 4 address. For more information, see RFC 1035. <\/td><\/tr>
Syntax:<\/strong>owner class ttl<\/em> A<\/strong> address_IP_v4<\/em><\/td><\/tr>
Example :<\/strong>host1.example.microsoft.com<\/a>. IN A 127.0.0.1 <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

AAAA<\/h2>\n\n
Description:<\/strong> AAAA resource record (IPv6 host address). Maps a DNS domain name to a 128-bit Internet Protocol (IP) version 6 address. For more information, see RFC 1886. <\/td><\/tr>
Syntax:<\/strong>owner class ttl<\/em> AAAA<\/strong> address_IP_v6<\/em><\/td><\/tr>
Example :<\/strong>ipv6_host1.example.microsoft.com<\/a>. IN AAAA 4321:0:1:2:3:4:567:89ab <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

AFSDB<\/h2>\n\n
Description:<\/strong> AFSDB (Andrew File System Database) resource record. Maps a DNS domain name in the server_host_name<\/em> field to the host name of a server belonging to a server subtype. TheSubtype<\/em> field can have one of these recognized and supported values:Value 1<\/strong> indicates that the server is an AFS version 3.0 volume location server for the named AFS cell. Value 2<\/strong> indicates that the server is an authenticated name server that maintains the root cell directory node for the server using the OSF (Open Software Foundation) DCE or HP\/Apollo NCA (Network Computing Architecture) authenticated cell name system. For more information, see RFC 1183. <\/td><\/tr>
Syntax:<\/strong>owner ttl class<\/em> AFSDB<\/strong> subtype server_host_name<\/em><\/td><\/tr>
Example:<\/strong>example.microsoft.com<\/a>. AFSDB 1 afs-server1.example.microsoft.com<\/a> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

CNAME<\/h2>\n\n
Description:<\/strong>CNAME (canonical name) resource record. Maps a DNS domain name with an alias, or secondary, in the owner<\/em> field to a canonical or primary DNS domain name, specified in the canonical_name<\/em> field. The canonical or primary DNS domain name used in the data is mandatory and must be convertible to a valid DNS domain name in the namespace. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> CNAME<\/strong> canonical_name<\/em><\/td><\/tr>
Example :<\/strong>aliasname.example.microsoft.com<\/a>. CNAME truename.example.microsoft.com<\/a> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

HINFO<\/h2>\n\n
Description:<\/strong>HINFO resource record (host information). Specifies the type of processor and operating system in the type_processor<\/em> and type_operating_system<\/em> fields, respectively, for the DNS domain name of the host in the owner<\/em> field. The most common processor and operating system types are listed in RFC 1700. This information can be used by application protocols such as FTP, which use special procedures to communicate with computers corresponding to a specific type of processor and operating system. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> HINFO <\/strong> processor_type operating_system_type<\/em><\/td><\/tr>
Example :<\/strong>my-computer-name.example.microsoft.com<\/a>. HINFO INTEL-386 WIN32 <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

MX<\/h2>\n\n
Description:<\/strong> MX resource record (mail server). Specifies message routing to a mail server host, as specified in mail_server_host<\/em>, for messages sent to a domain name specified in the owner<\/strong> field. 2-digit preference value indicating the order chosen in the event of multiple server hosts being specified. Each server host must have a corresponding A resource record (host address) in a valid zone. For more information, see RFC 1035. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> MX<\/strong> host_server_messaging preference<\/em><\/td><\/tr>
Example:<\/strong>example.microsoft.com<\/a>. MX 10 mailserver1.example.microsoft.com<\/a> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

NS<\/h2>\n\n
Description:<\/strong> Used to map a DNS domain name, as specified in owner<\/strong>, onto the names of hosts running DNS servers specified in the domain_server_name<\/em> field.<\/td><\/tr>
Syntax:<\/strong>owner ttl IN <\/em> NS<\/strong> server_domain_name<\/em><\/td><\/tr>
Example:<\/strong>example.microsoft.com<\/a>. IN NS nameserver1.example.microsoft.com<\/a> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

PTR<\/h2>\n\n
Description:<\/strong> PTR resource record (pointer). Points from the name contained in owner<\/strong> to another location in the DNS namespace as specified in target_domain_name<\/em>. Typically used in special domains such as the in-addr.arpa<\/a> domain tree to perform indirect address-name lookups. Most often, each record contains information that points to another DNS domain name location, such as a matching A resource (host address) record in a direct search zone. For more information, see RFC 1035. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> PTR<\/strong> target_domain_name<\/em><\/td><\/tr>
Example :<\/strong>1.0.0.10.in-addr.arpa<\/a>. PTR host.example.microsoft.com<\/a> <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

RP<\/h2>\n\n
Description:<\/strong> RP resource record (responsible person). Specifies a domain mailbox name for a responsible person in mailbox_name<\/em>. This name is then mapped to a domain name in text_record_name<\/em>, for which TXT resource records exist in the same zone. When RP records are used in DNS queries, additional queries are used to retrieve the associated TXT (text) resource record information. For more information, see RFC 1183. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> RP<\/strong> letter_box_name text_recording_name<\/em><\/td><\/tr>
Example:<\/strong>example.microsoft.com<\/a>. RP admin.example.microsoft.com<\/a>. admin-info.example.microsoft.com<\/a>.admin-info.example.microsoft.com<\/a>. TXT “Joe Administrator, (555) 555-0110” <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

SOA<\/h2>\n\n
Description:<\/strong>Name source resource record (SOA; Start of Authority). Indicates the original name of the zone and contains the name of the server which is the main source of information on the zone. It also indicates other basic properties of the zone. The SOA resource record is always the first record in a standard zone. It indicates which DNS server created it first, or which is currently the zone’s main server. It is also used to store other properties such as version information and timeouts that affect zone renewal or expiration. These properties affect the frequency of transfers between the zone’s reference servers. For more information, see Managing authority records<\/a>.RemarksIn<\/strong>the example below, the owner (main DNS server) is specified as “@”, because the domain name is “@”. @”, as the domain name is identical to the origin of all zone data(example.microsoft.com<\/a>.). This is a standard notation convention for resource records, frequently used in SOA registration. <\/td><\/tr>
Syntax:<\/strong>owner class <\/em> SOA<\/strong> server_names person_responsible (serial_number refresh_interval interval_before_new_attempt expiration minimum_lifetime)<\/em><\/td><\/tr>
Example :<\/strong>@ IN SOA serveurnoms.example.microsoft.com<\/a>. postmaster.example.microsoft.com<\/a>. ( 1 ; serial number 3600 ; update [1h] 600 ; retry [10m] 86400 ; expiry [1d] 3600 ) ; TTL min [1h] <\/td><\/tr><\/tbody><\/table><\/figure>\n\n

SRV<\/h2>\n\n
Description: <\/strong>Service locator resource (SRV) record. Allows multiple servers offering a similar TCP\/IP service to be located using a single DNS query. This record lets you manage a list of servers for a specific server port and transport protocol type, ranked in order of preference for a DNS domain name. For example, in DNS Windows Server 2003, this record allows you to locate domain controllers that use the LDAP (Lightweight Directory Access Protocol) service via TCP port 389,The purposes of each of the specialized fields used in an SRV resource record are as follows:service:<\/strong> Symbolic name for the desired service. For common services, a reserved universal symbolic name such as “_telnet” or “_smtp” is defined in RFC 1700. If a common service name is not defined in RFC 1700, a local or user-defined name may be used. Some frequently used TCP\/IP services, such as POP (Post Office Protocol), do not have a unique universal symbolic name. If RFC 1700 assigns a name to the service indicated in this field, the name defined by the RFC is the only name allowed. Only locally defined services can be named locally. protocol:<\/strong> Indicates the type of transport protocol. Typically, this is TCP or UDP, although any of the transport protocols named in RFC 1700 may be used.name:<\/strong> DNS domain name to which this resource record refers. The SRV resource record is unique among other DNS record types in that it is not used for searching or querying.priority:<\/strong> Defines the preference for a host specified in the target<\/em> field. DNS clients searching for SRV resource records try to contact the first accessible host with the lowest preference value specified here. Although target<\/em> hosts have the same preference value, they can be queried in random order. The range of preference values is between 0 and 65535.weight:<\/strong> Can be used in conjunction with preference to provide a load-balancing mechanism between multiple servers that are specified in the target<\/strong> field and all match the same preference level. When selecting a target server host from among servers of the same preference, this value can be used to add an additional preference level to determine the exact order or balancing of the selection, for target hosts used in the response to an SRV request. When a non-zero value is used, hosts with the same preference are tested in proportion to the weight of this value. The range of values is from 1 to 65535. If load balancing is not required, use a value of 0 in this field to make the record easier to read.port:<\/strong> Port of the server on the target<\/strong> host offering the service specified in the service<\/em> field. The port number range is 0 to 65535, although the number is usually a known port number reserved for the service, as defined in RFC 1700. Unassigned ports can be used if required.target:<\/strong> Specifies the DNS domain name of the host offering the type of service requested. Each host name used must have a corresponding A resource record (host address) in the DNS namespace. A single dot (.) can be used in this field to forcefully indicate that the requested service, specified in this SRV resource record, is not available for this DNS domain name. For more information, see the online help document “A DNS RR for specifying the location of services (DNS SRV)”. <\/td><\/tr>
Syntax :<\/strong>service.protocol.name ttl class <\/em> SRV <\/strong> preference target port weight<\/em><\/td><\/tr>
Example :<\/strong>_ldap._tcp._msdcs SRV 0 0 389 dc1.example.microsoft.com<\/a> SRV 10 0 389 dc2.example.microsoft.com<\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n\n

TXT<\/h2>\n\n
Description: <\/strong>TXT (text) resource record. Maps a DNS domain name specified in the owner<\/em> field to a string in the text_string<\/em> field for use as descriptive text. For more information, see RFC 1035. <\/td><\/tr>
Syntax:<\/strong>owner ttl class <\/em> TXT<\/strong> text_string<\/em><\/td><\/tr>
Example:<\/strong>example.microsoft.com<\/a>. TXT “This is an example of additional domain name information.” <\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

All resource records have a defined format that uses the same first-level fields, as described in the following table. A Description: A resource record (host address). Maps a DNS domain name to a 32-bit Internet Protocol (IP) version 4 address. For more information, see RFC 1035. Syntax:owner class ttl A address_IP_v4 Example :host1.example.microsoft.com. IN A […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"doc_category":[136],"doc_tag":[],"class_list":["post-27991","docs","type-docs","status-publish","hentry","doc_category-web-hosting"],"year_month":"2026-05","word_count":1543,"total_views":0,"reactions":{"happy":0,"normal":0,"sad":0},"author_info":{"name":"Support","author_nicename":"support","author_url":"https:\/\/www.cheops-technology.ch\/en\/author\/support\/"},"doc_category_info":[{"term_name":"Web hosting","term_url":"https:\/\/www.cheops-technology.ch\/en\/docs-category\/web-hosting\/"}],"doc_tag_info":[],"_links":{"self":[{"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/docs\/27991","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/comments?post=27991"}],"version-history":[{"count":1,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/docs\/27991\/revisions"}],"predecessor-version":[{"id":27993,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/docs\/27991\/revisions\/27993"}],"wp:attachment":[{"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/media?parent=27991"}],"wp:term":[{"taxonomy":"doc_category","embeddable":true,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/doc_category?post=27991"},{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/www.cheops-technology.ch\/en\/wp-json\/wp\/v2\/doc_tag?post=27991"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}