📄 rfc1035.4up.ps
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(upper case and a through z in lower case) s5 335 M(<digit> ::= any one of the ten digits 0 through 9) s5 309 M(Note that while upper and lower case letters are allowed in domain) s5 296 M(names, no significance is attached to the case. That is, two names with) s5 283 M(the same spelling but different case are to be treated as if identical.) s5 257 M(The labels must follow the rules for ARPANET host names. They must) s5 244 M(start with a letter, end with a letter or digit, and have as interior) s5 231 M(characters only letters, digits, and hyphen. There are also some) s5 218 M(restrictions on the length. Labels must be 63 characters or less.) s5 192 M(For example, the following strings identify hosts in the Internet:) s5 166 M(A.ISI.EDU XX.LCS.MIT.EDU SRI-NIC.ARPA) s5 140 M(2.3.2. Data Transmission Order) s5 114 M(The order of transmission of the header and data described in this) s5 101 M(document is resolved to the octet level. Whenever a diagram shows a) s5 49 M(Mockapetris [Page 8]) s_R_RS%%Page: (9-12) 3%%BeginPageSetup_S24 818 translate%Page: (9) 9%BeginPageSetup_S% N-up sub-page 1/40 -392 translate0.490859 dup scale/pagenum 9 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1035.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1035.txt) def% User defined strings:/fmodstr (Tue Nov 24 00:00:00 1987) def/pagenumstr (9) def/user_header_p true def/user_header_left_str (RFC1035) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 9 of 56) def%%EndPageSetupdo_header5 751 M(RFC 1035 Domain Implementation and Specification November 1987) s5 712 M(group of octets, the order of transmission of those octets is the normal) s5 699 M(order in which they are read in English. For example, in the following) s5 686 M(diagram, the octets are transmitted in the order they are numbered.) s5 660 M( 0 1) s5 647 M( 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5) s5 634 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 621 M( | 1 | 2 |) s5 608 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 595 M( | 3 | 4 |) s5 582 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 569 M( | 5 | 6 |) s5 556 M( +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+) s5 530 M(Whenever an octet represents a numeric quantity, the left most bit in) s5 517 M(the diagram is the high order or most significant bit. That is, the bit) s5 504 M(labeled 0 is the most significant bit. For example, the following) s5 491 M(diagram represents the value 170 \(decimal\).) s5 465 M( 0 1 2 3 4 5 6 7) s5 452 M( +-+-+-+-+-+-+-+-+) s5 439 M( |1 0 1 0 1 0 1 0|) s5 426 M( +-+-+-+-+-+-+-+-+) s5 400 M(Similarly, whenever a multi-octet field represents a numeric quantity) s5 387 M(the left most bit of the whole field is the most significant bit. When) s5 374 M(a multi-octet quantity is transmitted the most significant octet is) s5 361 M(transmitted first.) s5 335 M(2.3.3. Character Case) s5 309 M(For all parts of the DNS that are part of the official protocol, all) s5 296 M(comparisons between character strings \(e.g., labels, domain names, etc.\)) s5 283 M(are done in a case-insensitive manner. At present, this rule is in) s5 270 M(force throughout the domain system without exception. However, future) s5 257 M(additions beyond current usage may need to use the full binary octet) s5 244 M(capabilities in names, so attempts to store domain names in 7-bit ASCII) s5 231 M(or use of special bytes to terminate labels, etc., should be avoided.) s5 205 M(When data enters the domain system, its original case should be) s5 192 M(preserved whenever possible. In certain circumstances this cannot be) s5 179 M(done. For example, if two RRs are stored in a database, one at x.y and) s5 166 M(one at X.Y, they are actually stored at the same place in the database,) s5 153 M(and hence only one casing would be preserved. The basic rule is that) s5 140 M(case can be discarded only when data is used to define structure in a) s5 127 M(database, and two names are identical when compared in a case) s5 114 M(insensitive manner.) s5 49 M(Mockapetris [Page 9]) s_R%Page: (10) 10%BeginPageSetup_S% N-up sub-page 2/4278 -392 translate0.490859 dup scale/pagenum 10 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1035.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1035.txt) def% User defined strings:/fmodstr (Tue Nov 24 00:00:00 1987) def/pagenumstr (10) def/user_header_p true def/user_header_left_str (RFC1035) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 10 of 56) def%%EndPageSetupdo_header5 751 M(RFC 1035 Domain Implementation and Specification November 1987) s5 712 M(Loss of case sensitive data must be minimized. Thus while data for x.y) s5 699 M(and X.Y may both be stored under a single location x.y or X.Y, data for) s5 686 M(a.x and B.X would never be stored under A.x, A.X, b.x, or b.X. In) s5 673 M(general, this preserves the case of the first label of a domain name,) s5 660 M(but forces standardization of interior node labels.) s5 634 M(Systems administrators who enter data into the domain database should) s5 621 M(take care to represent the data they supply to the domain system in a) s5 608 M(case-consistent manner if their system is case-sensitive. The data) s5 595 M(distribution system in the domain system will ensure that consistent) s5 582 M(representations are preserved.) s5 556 M(2.3.4. Size limits) s5 530 M(Various objects and parameters in the DNS have size limits. They are) s5 517 M(listed below. Some could be easily changed, others are more) s5 504 M(fundamental.) s5 478 M(labels 63 octets or less) s5 452 M(names 255 octets or less) s5 426 M(TTL positive values of a signed 32 bit number.) s5 400 M(UDP messages 512 octets or less) s5 374 M(3. DOMAIN NAME SPACE AND RR DEFINITIONS) s5 348 M(3.1. Name space definitions) s5 322 M(Domain names in messages are expressed in terms of a sequence of labels.) s5 309 M(Each label is represented as a one octet length field followed by that) s5 296 M(number of octets. Since every domain name ends with the null label of) s5 283 M(the root, a domain name is terminated by a length byte of zero. The) s5 270 M(high order two bits of every length octet must be zero, and the) s5 257 M(remaining six bits of the length field limit the label to 63 octets or) s5 244 M(less.) s5 218 M(To simplify implementations, the total length of a domain name \(i.e.,) s5 205 M(label octets and label length octets\) is restricted to 255 octets or) s5 192 M(less.) s5 166 M(Although labels can contain any 8 bit values in octets that make up a) s5 153 M(label, it is strongly recommended that labels follow the preferred) s5 140 M(syntax described elsewhere in this memo, which is compatible with) s5 127 M(existing host naming conventions. Name servers and resolvers must) s5 114 M(compare labels in a case-insensitive manner \(i.e., A=a\), assuming ASCII) s5 101 M(with zero parity. Non-alphabetic codes must match exactly.) s5 49 M(Mockapetris [Page 10]) s_R%Page: (11) 11%BeginPageSetup_S% N-up sub-page 3/40 -794 translate0.490859 dup scale/pagenum 11 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1035.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1035.txt) def% User defined strings:/fmodstr (Tue Nov 24 00:00:00 1987) def/pagenumstr (11) def/user_header_p true def/user_header_left_str (RFC1035) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 11 of 56) def%%EndPageSetupdo_header5 751 M(RFC 1035 Domain Implementation and Specification November 1987) s5 712 M(3.2. RR definitions) s5 686 M(3.2.1. Format) s5 660 M(All RRs have the same top level format shown below:) s5 634 M( 1 1 1 1 1 1) s5 621 M( 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5) s5 608 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 595 M( | |) s5 582 M( / /) s5 569 M( / NAME /) s5 556 M( | |) s5 543 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 530 M( | TYPE |) s5 517 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 504 M( | CLASS |) s5 491 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 478 M( | TTL |) s5 465 M( | |) s5 452 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 439 M( | RDLENGTH |) s5 426 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|) s5 413 M( / RDATA /) s5 400 M( / /) s5 387 M( +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+) s5 348 M(where:) s5 322 M(NAME an owner name, i.e., the name of the node to which this) s5 309 M( resource record pertains.) s5 283 M(TYPE two octets containing one of the RR TYPE codes.) s5 257 M(CLASS two octets containing one of the RR CLASS codes.) s5 231 M(TTL a 32 bit signed integer that specifies the time interval) s5 218 M( that the resource record may be cached before the source) s5 205 M( of the information should again be consulted. Zero) s5 192 M( values are interpreted to mean that the RR can only be) s5 179 M( used for the transaction in progress, and should not be) s5 166 M( cached. For example, SOA records are always distributed) s5 153 M( with a zero TTL to prohibit caching. Zero values can) s5 140 M( also be used for extremely volatile data.) s5 114 M(RDLENGTH an unsigned 16 bit integer that specifies the length in) s5 101 M( octets of the RDATA field.) s5 49 M(Mockapetris [Page 11]) s_R%Page: (12) 12%BeginPageSetup_S% N-up sub-page 4/4278 -794 translate0.490859 dup scale/pagenum 12 def/fname (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/rfc1035.txt) def/fdir (/usr/local/share/doc/rfc/Mirrors/ftp.isi.edu/in-notes/) def/ftail (rfc1035.txt) def% User defined strings:/fmodstr (Tue Nov 24 00:00:00 1987) def/pagenumstr (12) def/user_header_p true def/user_header_left_str (RFC1035) def/user_header_center_str (RFC.net) def/user_header_right_str (Page 12 of 56) def%%EndPageSetupdo_header5 751 M(RFC 1035 Domain Implementation and Specification November 1987) s5 712 M(RDATA a variable length string of octets that describes the) s5 699 M( resource. The format of this information varies) s5 686 M( according to the TYPE and CLASS of the resource record.) s5 660 M(3.2.2. TYPE values) s5 634 M(TYPE fields are used in resource records. Note that these types are a) s5 621 M(subset of QTYPEs.) s5 595 M(TYPE value and meaning) s5 569 M(A 1 a host address) s5 543 M(NS 2 an authoritative name server) s5 517 M(MD 3 a mail destination \(Obsolete - use MX\)) s5 491 M(MF 4 a mail forwarder \(Obsolete - use MX\)) s5 465 M(CNAME 5 the canonical name for an alias) s5 439 M(SOA 6 marks the start of a zone of authority) s5 413 M(MB 7 a mailbox domain name \(EXPERIMENTAL\)) s5 387 M(MG 8 a mail group member \(EXPERIMENTAL\)) s5 361 M(MR 9 a mail rename domain name \(EXPERIMENTAL\)) s5 335 M(NULL 10 a null RR \(EXPERIMENTAL\)) s5 309 M(WKS 11 a well known service description) s5 283 M(PTR 12 a domain name pointer) s5 257 M(HINFO 13 host information) s5 231 M(MINFO 14 mailbox or mail list information) s5 205 M(MX 15 mail exchange) s5 179 M(TXT 16 text strings) s5 153 M(3.2.3. QTYPE values) s5 127 M(QTYPE fields appear in the question part of a query. QTYPES are a) s5 114 M⌨️ 快捷键说明
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