Table Of Contents

Resource Records

Resource Records

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Resource records comprise the data within a DNS zone. There is no fixed limit to the number of resource records a zone can own. In general, there can be zero, one, or more resource records of a given type. However, there are constraints on the number of certain types of records a zone can have.

All resource records have the following required entries:

•Name—Name (host) that owns the record, such as example.com.

•Class (not required for all formats)—DNS supports only the IN (Internet) class of record.

•TTL (time to live)—Amount of time to store the record in cache, in seconds. If you do not include a TTL, Network Registrar uses the zone default TTL, defined in the SOA resource record.

•Type—Type of the record, such as A, NS, SOA, and MX. There are many types that various RFCs define, although ten or fewer are in common use.

•Record data—Data types whose format and meaning varies with record type.

Table A-1 lists all the resource record types Network Registrar supports. It provides the field syntax and the field descriptions, as well as how the fields are represented in the Network Registrar GUI.

Table A-1 Resource Records 

This record...	Data type...	Means...	The fields are...	As described in...
A	1	Host Address— Name-to- address mapping for the zone	owner class ttl A address CLI entry example: nrcmd> zone example.com addRR host123 3600        IN A 192.168.40.123 100 Ok host123 3600 IN A 192.168.40.123 GUI tab A: Name, TTL, Class, Type, Address •Name (owner)—Hostname expressed as an FQDN •Address (address)—32-bit IP address in dotted decimal form There must be at least one A record for each host address.	RFC 1035
A6 (will replace AAAA records)	38	IPv6 Address—	owner class ttl A6 address CLI entry example: nrcmd> zone example.com addRR host456 A6        0 1345:c1:ca11:1:1234:5678:9abc:def0 100 Ok host456 IN A6 0 1345:c1:ca11:1234:5678:9abc:def0 GUI tab Generic: Name, TTL, Class, Type, Data Data (address) is in the format: prefixlength suffixaddr prefixname 0 2345:00c1:ca11:0001:1234:5678:9abc:def0 prefixlength—Must be 0 (the numbers 1 through 128 are currently not supported) suffixaddr—IPv6 address (see below) prefixname—Name of the prefix, encoded as a domain name The suffix address is an IPv6 address encoded in network order (high-order octet first). There must be exactly enough octets in this field to contain a number of bits equal to 128 minus prefix length, with 0 to 7 leading pad bits to make this field an integral number of octets. Pad bits, if present, must be set to zero when loading a zone file and ignored on reception. For example: 2001:0:734c:c0::	RFC 2874
AAAA	28	SIPv6 Address—	owner class ttl AAAA address CLI entry example: nrcmd> zone example.com addRR host456 AAAA        1345:c1:ca11:1:1234:5678:9abc:def0" 100 Ok host456 IN AAAA 1345:c1:ca11:1234:5678:9abc:def0 GUI tab Generic: Name, TTL, Class, Type, Data Data (address)—IPv6 address format of eight sets of four hexadecimal digits, separated by colons. The first set of four digits is the high-order 16 bits of the address. You can omit leading zeroes in sets and omit a value in a set if the value of the set is zero.	RFC 1884
AFSDB	18	Andrew File System (AFS) Data Base—	owner class ttl AFSDB subtype hostname CLI entry example: nrcmd> zone example.com addRR host4 AFSDB        1 AFSDBhost.example.com. 100 Ok host456 IN AFSDB 1 AFSDBhost.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (subtype hostname)— •subtype— –1—AFS cell database server –2—DCE authentication name server •hostname—Domain name of host that has a server for the cell named by the owner	RFC 1183
CNAME	5	Canonical Name— Aliases or nicknames	owner class ttl CNAME canonicalname CLI entry example: nrcmd> zone example.com addRR host456 CNAME        host1234 100 Ok host456 IN CNAME host1234.example.com. GUI tab CNAME: Name, TTL, Class, Type, Host •Name (owner)—Alias name •Host (canonicalname)—Canonical or primary host of the owner You cannot have any other resource records associated with a CNAME. Aliases are useful when you want the outside world to know a single, easily remembered name. You can also use aliases when a host changes its name. In that case, make sure that you have a CNAME pointer so that when people use the original name, that it can be resolved to the newer one.	RFC 1035
HINFO	13	Host Info— Hardware and software information for the host	owner class ttl HINFO cpu os CLI entry example: nrcmd> zone example.com addRR host5 HINFO        CPU1 OS2 100 Ok host5 IN HINFO "CPU1" "OS2" GUI tab Generic: Name, TTL, Class, Type, Data Data (cpu os)— •cpu—CPU type character string •os—Operating system type character string	RFC 1035
ISDN	20	Integrated Services Digital Network (ISDN) Address—	owner class ttl ISDN ISDNnumber [subaddr] CLI entry example: nrcmd> zone example.com addRR host6 ISDN        ISDN88888 100 Ok host6 IN ISDN "ISDN88888" "" GUI tab Generic: Name, TTL, Class, Type, Data Data (ISDNnumber subaddr)— •ISDN-number—ISDN number of the owner and Direct Dial In, if any •subaddr—Optional ISDN subaddress string	RFC 1183
MB	7	Mailbox Domain Name—	owner class ttl MB mbox CLI entry example: nrcmd> zone example.com addRR host7 MB        mailbox.example.com. 100 Ok host7 IN MB mailbox.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (mbox)—Domain name of the host with the specified mailbox.	RFC 1035
MG	8	Mail Group Member—	owner class ttl MG mgroup CLI entry example: nrcmd> zone example.com addRR host7 MG        mbgroup.example.com. 100 Ok host7 IN MG mbgroup.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (mgroup)—Domain name of the mailbox group (mailing list).	RFC 1035
MINFO	14	Mailbox Info—	owner class ttl MINFO respmbox errormbox CLI entry example: nrcmd> zone example.com addRR host7 MINFO        resp.example.com. error.example.com. 100 Ok host7 IN MINFO resp.example.com. error.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (respmbox errormbox)— •respmbox—Mailbox responsible for the mailing list or mailbox for the owner mailbox •errormbox—Mailbox to receive error messages for the owner mailbox	RFC 1035
MR	9	Mail Rename—	owner class ttl MR newmbox CLI entry example: nrcmd> zone example.com addRR host7 MR        renamemb.example.com. 100 Ok host7 IN MR renamemb.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (newmbox)—Mailbox name to rename the owner mailbox	RFC 1035
MX	15	Mail Exchanger— Where to deliver the mail for a domain name	owner class ttl MX pref mxname CLI entry example: nrcmd> zone example.com addRR host8 MX 10        exchanger.example.com. 100 Ok host8 IN MX 10 exchanger.example.com. GUI tab MX: Name, TTL, Class, Type, Preference, Host •Name (owner)—Domain name of the host •Preference (pref)—16-bit integer for the preference for the record, with lower values having preference •Host (mxname)—Domain name of the mail exchanger for the owner	RFC 1035
NAPTR	35	Naming Authority Pointer— Produces a new domain label or Universal Resource Identifier (URI). You can then use DNS to look up services for many resource names that are not in domain name syntax.	owner class ttl NAPTR order pref flags service regexp replace CLI entry example: nrcmd> zone 8.6.4.e164.arpa addRR        4.3.2.1.6.7.9 naptr 100 10 u sip+E2U        /^.*$/sip:info@tele2.se/ . 100 Ok 4.3.2.1.6.7.8 IN NAPTR 100 10 "u" "sip+E2U" "/^.*$/sip:info@tele2.se/" nrcmd> dns reload GUI tab Generic: Name, TTL, Class, Type, Data Data (order pref flags service regexp replace)— •order—16-bit integer for the order in which to process the NAPTR records to ensure the correct ordering of rules, with low numbers processed before high numbers •pref—16-bit unsigned integer for the order in which to process NAPTR records with equal order values, with low numbers processed before high numbers •flags—Character-string containing flags to control aspects of rewriting and interpreting fields, single characters from the set [A-Z0-9] (case-insensitive); the S, A and U flags denote a terminal lookup, the P flag says that the remainder of the application-side algorithm should be carried out protocol-specific •service—Valid protocols or services •regexp—String containing a substitution expression applied to the original string held by the client to construct the next domain name to look up •replace—Next FQDN to query for NAPTR, SRV, or address records, depending on the value of the flags field Note You must reload the server after adding this resource record.	RFC 2915
NS	2	Name Server— Authoritative server for the zone	owner class ttl name NS nameserver CLI entry example: nrcmd> zone example.com addRR @ NS        DNSserv2.example.com. 100 Ok @ IN NS DNSserv2.example.com. GUI tab NS: Name, TTL, Class, Type, Server •Name (name)—Domain of the host ("at" symbol, @, if the same as the owner) •Server (nameserver)—Domain name of host authoritative for the class and domain Machines that provide name service must not reside in the owner domain. For each domain, you must have at least one NS record. NS records for a domain must exist in both the zone that delegates the domain and in the domain itself. NS record names must have an equivalent A record (they cannot point to an alias).	RFC 1035
NSAP	22	Network Service Access Point (NSAP) Address	owner class ttl NASP length NSAPaddr CLI entry example: nrcmd> zone example.com addRR host10 NSAP        4 23456789 100 Ok host10 IN NSAP 4 23456789 GUI tab Generic: Name, TTL, Class, Type, Data Data (length NSAPaddr)— •length—Number of octets in the NSAP address as defined by the various national and international authorities •NSAPaddr—Actual octet values assigned by the assigning authority, as a character string syntactically identical to that used in TXT and HINFO records.	RFC 1348
PTR	12	Pointer— Reverse mapping	owner class ttl PTR dname CLI entry example: nrcmd> zone example.com addRR        45.40.168.192.in-addr.arpa. PTR        host1234 100 Ok 45.40.168.192.in-addr.arpa. IN PTR host1234.example.com. GUI tab PTR: Name, TTL, Class, Type, Data Data (dname)—Domain name of host having the reverse record indicated by owner Used for reverse mapping, specifically in the in-addr.arpa zones for translation of addresses to names. PTRs use official names, not aliases. The name in a PTR record is the local IP address portion of the reverse name.	RFC 1035
RP	17	Responsible Person—	owner class ttl RP mbox txthost CLI entry example: nrcmd> zone example.com addRR host7 RP        resp.example.com. text.example.com. 100 Ok host7 IN RP resp.example.com. text.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (mbox txthost)— •mbox—Domain name of the mailbox for the responsible person •txthost—Domain name of host where TXT records exist	RFC 1183
RT	21	Route Through—	owner class ttl RT pref intermediatehost CLI entry example: nrcmd> zone example.com addRR host7 RT 10        routthru.example.com. 100 Ok host7 IN RT 10 routthru.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (pref intermediatehost)— •pref—16-bit integer for preference to give to this record among others of the same owner •intermediatehost—Domain name of host serving as intermediate to reach the owner	RFC 1183
SOA	6	Start of Authority— Every zone must have a single SOA record	owner class ttl SOA primeserver mbox (serial refresh retry expire minimum) CLI entry example: nrcmd> zone example.com addRR @ 172800 IN        SOA ns hostmaster 1 10800 3600        604800 86400 100 Ok @ IN SOA ns.example.com. hostmaster.example.com. 1 10800 3600 604800 86400 nrcmd> dns reload GUI tab SOA: Name, TTL, Contact e-mail address, Name of primary server, Serial number, Secondary refresh time, Secondary retry time, Secondary expire time, Minimum TTL •Name (owner)—FQDN of the zone •TTL (ttl)—Default TTL for all the records in the zone, if not indicated in the record •Name of primary server (primeserver)— Domain name of primary name server •Contact e-mail address (mbox)—Mailbox of the responsible person •Serial number (serial)—32-bit version number of the original copy of the zone •Secondary refresh time (refresh)—32-bit time interval before refreshing the zone •Secondary retry time (retry)—32-bit time interval before retrying a failed refresh •Secondary expire time (expire)—32-bit maximum time interval before declaring a zone no longer authoritative •Minimum TTL (minimum)—32-bit minimum TTL for all the records in the zone Note You must reload the server after adding this resource record.	RFC 1035
SRV	33	Server—	owner class ttl SRV priority weight port target CLI entry example: nrcmd> zone example.com addRR host2 SRV 10        1 60 host7.example.com. 100 Ok host2 IN SRV 10 1 60 host7.example.com. GUI tab Generic: Name, TTL, Class, Type, Data Data (priority weight port target)— •priority—16-bit priority to give the record among the owner SRV records •weight—16-bit load to give the record at the same priority level •port—16-bit port on which to run the service •target—Domain name of host running on the specified port Administrators can use several servers for a single domain, move services between hosts with little difficulty, and designate some hosts as primary servers for a service and others as backups. Clients ask for a specific service or protocol for a domain and receive the names of any available servers. See "Windows 2000 Interoperability," for how this record affects Windows 2000 servers.	RFC 2782
TXT	16	Text—	owner class ttl TXT textstrings CLI entry example: nrcmd> zone example.com addRR host2 TXT        this message 100 Ok host2 IN TXT "this message" GUI tab Generic: Name, TTL, Class, Type, Data Data (textstrings)—One or more text character strings less than or equal to 256 characters that can contain any type of information	RFC 1035
WKS	11	Well Known Services—	owner class ttl WKS addr protocol servicelist CLI entry example: nrcmd> zone example.com addRR host8 WKS        192.168.40.56 TCP TELNET 100 Ok host8 IN WKS 192.168.40.56 tcp telnet GUI tab Generic: Name, TTL, Class, Type, Data Data (addr protocol servicelist)— •addr—32-bit IP address •protocol—8-bit IP protocol number, which can be TCP or UDP •servicelist—Variable-length bit map in 8-bit multiples of services, which can be TIME, TELNET, FTP, or SMTP	RFC 1035
X25	19	X.25 Address—	owner class ttl X25 PSDNaddr CLI entry example: nrcmd> zone example.com addRR host9 IN X25        311061700956 100 Ok host9 IN X25 "311061700956" GUI tab Generic: Name, TTL, Class, Type, Data Data (PSDNaddr)—Character string of Public Switch Data Network (PSDN) address in X.121 numbering plan associated with the owner	RFC 1183