What are DNS resource records and how do we create them manually?

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DNS resource records will be created automatically when we install and configure DNS Server with it’s feature of dynamic update. DNS server dynamically updates many types of DNS resource records. You have to create some of the records manually when some types of computers don’t support dynamic update and some types of records can not be created dynamically. You can only create DNS resource records manually in standard primary and active directory integrated zones. You can’t create resource records in secondary zones. DNS server supports various types of records where each type of resource record has a different purpose. The list of all available record types are given below in a table.

Resource record TypeDescription of the resource record
AFS Database (AFSDB)Andrew File System Database (AFSDB) server record. Indicates the location of either of the following standard server subtypes: an AFS volume location (cell database) server or a Distributed Computing Environment (DCE) authenticated name server. Also, supports other user-defined server subtypes that use the AFSDB resource record format. (RFC 1183)
Alias (CNAME)Alias record. Indicates an alternate or alias DNS domain name for a name already specified in other resource record types used in this zone. The record is also known as the canonical name (CNAME) record type. (RFC 1035)
ATM Address (ATMA)ATM address (ATMA) record. Maps a DNS domain name to an ATM address.
Host (A)Host address (A) record. Maps a DNS domain name to a single 32-bit IP version 4 address. (RFC 1035)
Host Information (HINFO)Host Information (HINFO) record. Indicates RFC-1700 reserved character string values for CPU and operating system types for mapping to specific DNS host names. This information is used by application protocols such as FTP that can use special procedures when communicating between computers of the same CPU and OS type. (RFC 1035)
IPv6 Host (AAAA)Host address (AAAA) record for IPv6 hosts. Maps a DNS domain name to a single 128-bit IPv6 address. (RFC 1886)
ISDNIntegrated Services Digital Network (ISDN) record. Maps a DNS domain name to an ISDN telephone number. ISDN telephone numbers used with this record meet CCITT E.163/E.164 international telephone numbering standards. (RFC 1183)
Mail Exchanger (MX)Mail exchanger (MX) record. Provides message routing to a specified mail exchange host that is acting as a mail exchanger for a specified DNS domain name. MX records use a 16-bit integer to indicate host priority in message routing where multiple mail exchange hosts are specified. For each mail exchange host specified in this record type, a corresponding host address (A) type record is needed. (RFC 1035)
Mail Group (MG)Mail group (MG) record. Adds domain mailboxes, each specified by a mailbox (MB) record in the current zone, as members of a domain mailing group that is identified by name in this record. (RFC 1035)
Mail Box (MB)Mailbox (MB) record. Maps a specified domain mailbox name to a host that hosts this mailbox. (RFC 1035)
Mail Information (MINFO)Mailbox or mail list information (MINFO) record. Specifies a domain mailbox name to contact. This contact maintains a mail list or mailbox specified in this record. Also, specifies a mailbox for receiving error messages related to the mailing list or mailbox specified in this record. (RFC 1035)
Next Domain (NXT)Next (NXT) record. NXT resource records indicate the nonexistence of a name in a zone by creating a chain of all of the literal owner names in that zone. They also indicate what resource record types are present for an existing name.
Pointer (PTR)Pointer (PTR) record. Points to a location in the domain name space. PTR records are typically used in special domains to perform reverse lookups of address-to-name mappings. Each record provides simple data that points to some other location in the domain name space (usually a forward lookup zone). Where PTR records are used, no additional section processing is implied or caused by their presence. (RFC 1035)
Public Key (KEY)Public key (KEY) record. Stores a public key that is related to a DNS domain name. This public key can be of a zone, a user, or a host or other end entity. A KEY resource record is authenticated by a SIG resource record. A zone level key must sign KEYs.
Renamed Mailbox (MR)Renamed mailbox (MR) record. Specifies a domain mailbox name, which is the proper rename of an existing specified mailbox (specified in an existing mailbox or an MB-type record in the zone). The main use for an MR record is as a forwarding entry for a user who has moved to a different mailbox. If used, MR records do not cause additional section processing. (RFC 1035)
Responsible Person (RP)Responsible Person (RP) record. Specifies the domain mailbox name for a responsible person and maps this name to a domain name for which text (TXT) resource records exist. Where RP records are used in DNS queries, subsequent queries can be needed to retrieve the text (TXT) record information mapped using the RP record type. (RFC 1183)
Route Through (RT)Route Through (RT) record. Provides an intermediate-route-through binding for internal hosts that do not have their own direct wide area network (WAN) address. This record uses the same data format as the MX record type to indicate two required fields: a 16-bit integer that represents preference for each intermediate route and the DNS domain name for the route-through host as it appears elsewhere in an A, X25, or ISDN record for the zone. (RFC 1183)
Service Location (SRV)Service (SRV) record. Allows administrators to use several servers for a single DNS domain, to easily move a TCP/IP service from one host to another host with administration, and to designate some service provider hosts as primary servers for a service and other hosts as backups. DNS clients that use a SRV-type query ask for a specific TCP/IP service and protocol mapped to a specific DNS domain and receive the names of any available servers. (RFC 2052)
Signature (SIG)Cryptographic signature (SIG) record. Authenticates a resource record set of a particular type, class, and name and binds it to a time interval and the signer’s DNS domain name. This authentication and binding is done using cryptographic techniques and the signer’s private key. The signer is frequently the owner of the zone from which the resource record originated.
Text (TXT)Text (TXT) record. Holds a string of characters that serves as descriptive text to be associated with a specific DNS domain name. The semantics of the actual descriptive text used as data with this record type depends on the DNS domain where these records are located. (RFC 1035)
Well Known Services (WKS)Well Known Service (WKS) record. Describes the well-known TCP/IP services supported by a particular protocol on a particular IP address. WKS records provide TCP and UDP availability information for TCP/IP servers. If a server supports both TCP and UDP for a well-known service or if the server has multiple IP addresses that support a service, multiple WKS records are used. (RFC 1035)
X.25X.25 (X25) record. Maps a DNS domain name to a Public Switched Data Network (PSDN) address, such as X.121 addresses, which are typically used to identify each point of service located on a public X.25 network. (RFC 1183)

The step-by-step procedure to create one of the resource record “Alias (CNAME)” manually as follows:

  • Right click on forward or reverse lookup zone in the left pane of the DNS management console and click other new records
  • To show the types of records available to create, I have asked you to click on the other new records. You can also use direct option which is available after right click on zone, to create resource records like New Host, New Alias, New Mail Exchanger …etc.
  • Select the Alias(CNAME) and Click on create record – type alias name – Click browse and select appropriate FQDN of target host and click OK
  • Click done in the resource record type window
  • The new alias(CNAME) name for the target host will be created. You can test this record type by pinging from command line interface. You should get the reply from target host.

You can also create any other type of resource record in the same way, except some options. I have recorded all the screen shots of creating Alias(CNAME) resource record while creating on my server. I am attaching these screen shots in this post. Please go through it and enjoy learning MCSE.

You can also ask me any doubt about creating different types of resource records mentioned above. I will explain online in my interactive class. Write a comment about this topic using following form. Your comments helps me to improve the course content and will be useful to you and other readers of my blog.

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