DNS各种查询报文类型说明

A Address, code 1. Used for storing an IP address (specifically, an IPv4 32-bit address) associated with a domain name. Defined in . A6 IPv6 address, code 38. Relegated to Experimental status by , as are now regarded as more generally useful. Defined in . IPv6 address, code 28. Used for storing an IPv6 128-bit address associated with a domain name. Defined in . AFSDB AFS Data Base location, code 18. Not widely used, rather use instead. Defined in . Canonical name for a DNS alias, code 5. Note that if a domain name has a CNAME record associated with it, then it can not have any other record types. In addition, CNAME records should not point to domain names which themselves have associated CNAME records, so CNAME only provides one layer of indirection. Defined in . DNAME DNAME, code 39. A way to provide aliases for a whole domain, not just a single domain name as with . Defined in . DS Delegation signer, code 43. A major change to the way operates. Defined in . GPOS Geographical position, code 27, obsolete. Defined in . HINFO Host Information, code 13. Not widely used. Defined in . ISDN ISDN address, code 20. Not widely used. Defined in . KEY Public key as used in , code 25. Defined in . See also . KX Key Exchanger, code 36. Defined in . LOC Location information, code 29. Associates a geographical location with a domain name. Defined in . MB Mailbox, code 7. Not widely used. Defined in . . . MG Mail group member, code 8. Not widely used. Defined in . MINFO Mailbox or mailing list information, code 14. Defined in . MR Mail rename domain name, code 9. Not widely used. Defined in . Mail Exchanger, code 15. Each MX record specifies a domain name (which must have an A record associated with it) and a priority; a list of mail exchangers is then ordered by priority when delivering mail. MX records provide one level of indirection in mapping the domain part of an email address to a list of host names which are meant to receive mail for that domain name. Critical part of the infrastructure used to support email. Defined in . NAPTR Naming authority pointer, code 35. Used mostly for Internet telephony infrastructure as in . Defined in . NULL Null record, code 10. Not widely used. Defined in . Authoritative name server, code 2. Specifies a host name (which must have an A record associated with it), where DNS information can be found about the domain name to which the NS record is attached. NS records are the basic infrastructure on which DNS is built; they stitch together distributed zone files into a directed graph that can be efficiently searched. Defined in . NSAP Network service access point address, code 22. Allows OSI-style NSAPs to be stored in the DNS. Defined in . NSAP-PTR NSAP pointer, code 23, obsolete. Defined in . NXT Next domain, code 30, obsolete. Defined in . Domain name pointer, code 12. Provides a general indirection facility for DNS records. Most often used to provide a way to associate a domain name with an IPv4 address in the IN-ADDR.ARPA domain. Defined in . PX Pointer to X.400/RFC822 mail mapping information. Defined in . RP Responsible person, code 17. Defined in . RT Route through, code 21. Not widely used. Defined in . SIG Cryptographic public key signature, code 24. Defined in . Start of authority, code 6. Marks the start of a zone. Defined in . Server selection, code 33. Similar to records, generalised to any network service. Defined in . TKEY Transaction key, code 249. A way of distributing keys for records. Defined in . Transaction signature, code 250. Simple authentication for DNS transactions, using shared secret keys and hashing. Defined in . TXT Text string, code 16. Arbitrary binary data, up to 255 bytes in length. Defined in . WKS Well-known service, code 11. Information about which services are available at a host. Defined in . X25 X25 PSDN address, code 19. Not widely used. Defined in .