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Network Working Group R. Austein
Request for Comments: 1612 Epilogue Technology Corporation
Category: Standards Track J. Saperia
Digital Equipment Corporation
May 1994
DNS Resolver MIB Extensions
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Table of Contents
1. Introduction .............................................. 1
2. The SNMPv2 Network Management Framework ................... 2
2.1 Object Definitions ....................................... 2
3. Overview .................................................. 2
3.1 Resolvers ................................................ 3
3.2 Name Servers ............................................. 3
3.3 Selected Objects ......................................... 4
3.4 Textual Conventions ...................................... 4
4. Definitions ............................................... 5
5. Acknowledgements .......................................... 30
6. References ................................................ 30
7. Security Considerations ................................... 32
8. Authors' Addresses ........................................ 32
1. Introduction
This memo defines a portion of the Management Information Base (MIB)
for use with network management protocols in the Internet community.
In particular, it describes a set of extensions which instrument DNS
resolver functions. This memo was produced by the DNS working group.
With the adoption of the Internet-standard Network Management
Framework [4,5,6,7], and with a large number of vendor
implementations of these standards in commercially available
products, it became possible to provide a higher level of effective
network management in TCP/IP-based internets than was previously
available. With the growth in the use of these standards, it has
become possible to consider the management of other elements of the
infrastructure beyond the basic TCP/IP protocols. A key element of
Austein & Saperia [Page 1]
RFC 1612 DNS Resolver MIB May 1994 the TCP/IP infrastructure is the DNS. Up to this point there has been no mechanism to integrate the management of the DNS with SNMP-based managers. This memo provides the mechanisms by which IP-based management stations can effectively manage DNS resolver software in an integrated fashion. We have defined DNS MIB objects to be used in conjunction with the Internet MIB to allow access to and control of DNS resolver software via SNMP by the Internet community. 2. The SNMPv2 Network Management Framework The SNMPv2 Network Management Framework consists of four major components. They are: o RFC 1442 which defines the SMI, the mechanisms used for describing and naming objects for the purpose of management. o STD 17, RFC 1213 defines MIB-II, the core set of managed objects for the Internet suite of protocols. o RFC 1445 which defines the administrative and other architectural aspects of the framework. o RFC 1448 which defines the protocol used for network access to managed objects. The Framework permits new objects to be defined for the purpose of experimentation and evaluation. 2.1. Object Definitions Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) defined in the SMI. In particular, each object object type is named by an OBJECT IDENTIFIER, an administratively assigned name. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the descriptor, to refer to the object type. 3. Overview In theory, the DNS world is pretty simple. There are two kinds of entities: resolvers and name servers. Resolvers ask questions. Name servers answer them. The real world, however, is not so simple. Austein & Saperia [Page 2]
RFC 1612 DNS Resolver MIB May 1994 Implementors have made widely differing choices about how to divide DNS functions between resolvers and servers. They have also constructed various sorts of exotic hybrids. The most difficult task in defining this MIB was to accommodate this wide range of entities without having to come up with a separate MIB for each. We divided up the various DNS functions into two, non-overlapping classes, called "resolver functions" and "name server functions." A DNS entity that performs what we define as resolver functions contains a resolver, and therefore must implement the MIB groups required of all resolvers which are defined in this module. Some resolvers also implement "optional" functions such as a cache, in which case they must also implement the cache group contained in this MIB. A DNS entity which implements name server functions is considered to be a name server, and must implement the MIB groups required for name servers which are defined in a separate module. If the same piece of software performs both resolver and server functions, we imagine that it contains both a resolver and a server and would thus implement both the DNS Server and DNS Resolver MIBs. 3.1. Resolvers In our model, a resolver is a program (or piece thereof) which obtains resource records from servers. Normally it does so at the behest of an application, but may also do so as part of its own operation. A resolver sends DNS protocol queries and receives DNS protocol replies. A resolver neither receives queries nor sends replies. A full service resolver is one that knows how to resolve queries: it obtains the needed resource records by contacting a server authoritative for the records desired. A stub resolver does not know how to resolve queries: it sends all queries to a local name server, setting the "recursion desired" flag to indicate that it hopes that the name server will be willing to resolve the query. A resolver may (optionally) have a cache for remembering previously acquired resource records. It may also have a negative cache for remembering names or data that have been determined not to exist. 3.2. Name Servers A name server is a program (or piece thereof) that provides resource records to resolvers. All references in this document to "a name server" imply "the name server's role"; in some cases the name server's role and the resolver's role might be combined into a single program. A name server receives DNS protocol queries and sends DNS protocol replies. A name server neither sends queries nor receives replies. As a consequence, name servers do not have caches. Normally, a name server would expect to receive only those queries to which it could respond with authoritative information. However, if a Austein & Saperia [Page 3]
RFC 1612 DNS Resolver MIB May 1994 name server receives a query that it cannot respond to with purely authoritative information, it may choose to try to obtain the necessary additional information from a resolver which may or may not be a separate process. 3.3. Selected Objects Many of the objects included in this memo have been created from information contained in the DNS specifications [1,2], as amended and clarified by subsequent host requirements documents [3]. Other objects have been created based on experience with existing DNS management tools, expected operational needs, the statistics generated by existing DNS implementations, and the configuration files used by existing DNS implementations. These objects have been ordered into groups as follows: o Resolver Configuration Group o Resolver Counter Group o Resolver Lame Delegation Group o Resolver Cache Group o Resolver Negative Cache Group o Resolver Optional Counter Group This information has been converted into a standard form using the SNMPv2 SMI defined in [9]. For the most part, the descriptions are influenced by the DNS related RFCs noted above. For example, the descriptions for counters used for the various types of queries of DNS records are influenced by the definitions used for the various record types found in [2]. 3.4. Textual Conventions Several conceptual data types have been introduced as a textual conventions in the DNS Server MIB document and have been imported into this MIB module. These additions will facilitate the common understanding of information used by the DNS. No changes to the SMI or the SNMP are necessary to support these conventions. Readers familiar with MIBs designed to manage entities in the lower layers of the Internet protocol suite may be surprised at the number of non-enumerated integers used in this MIB to represent values such as DNS RR class and type numbers. The reason for this choice is simple: the DNS itself is designed as an extensible protocol, Austein & Saperia [Page 4]
RFC 1612 DNS Resolver MIB May 1994 allowing new classes and types of resource records to be added to the protocol without recoding the core DNS software. Using non- enumerated integers to represent these data types in this MIB allows the MIB to accommodate these changes as well. 4. Definitions DNS-RESOLVER-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, IpAddress, Counter32, Integer32 FROM SNMPv2-SMI TEXTUAL-CONVENTION, RowStatus, DisplayString FROM SNMPv2-TC MODULE-COMPLIANCE, OBJECT-GROUP FROM SNMPv2-CONF dns, DnsName, DnsNameAsIndex, DnsClass, DnsType, DnsQClass, DnsQType, DnsTime, DnsOpCode, DnsRespCode FROM DNS-SERVER-MIB; -- DNS Resolver MIB dnsResMIB MODULE-IDENTITY LAST-UPDATED "9401282250Z" ORGANIZATION "IETF DNS Working Group" CONTACT-INFO " Rob Austein Postal: Epilogue Technology Corporation 268 Main Street, Suite 283 North Reading, MA 10864 US Tel: +1 617 245 0804 Fax: +1 617 245 8122 E-Mail: sra@epilogue.com Jon Saperia Postal: Digital Equipment Corporation 110 Spit Brook Road ZKO1-3/H18 Nashua, NH 03062-2698 US Tel: +1 603 881 0480 Fax: +1 603 881 0120 E-mail: saperia@zko.dec.com" DESCRIPTION "The MIB module for entities implementing the client (resolver) side of the Domain Name System (DNS) protocol." Austein & Saperia [Page 5]
RFC 1612 DNS Resolver MIB May 1994 ::= { dns 2 } dnsResMIBObjects OBJECT IDENTIFIER ::= { dnsResMIB 1 } -- (Old-style) groups in the DNS resolver MIB. dnsResConfig OBJECT IDENTIFIER ::= { dnsResMIBObjects 1 } dnsResCounter OBJECT IDENTIFIER ::= { dnsResMIBObjects 2 } dnsResLameDelegation OBJECT IDENTIFIER ::= { dnsResMIBObjects 3 } dnsResCache OBJECT IDENTIFIER ::= { dnsResMIBObjects 4 } dnsResNCache OBJECT IDENTIFIER ::= { dnsResMIBObjects 5 } dnsResOptCounter OBJECT IDENTIFIER ::= { dnsResMIBObjects 6 } -- Resolver Configuration Group dnsResConfigImplementIdent OBJECT-TYPE SYNTAX DisplayString MAX-ACCESS read-only STATUS current DESCRIPTION "The implementation identification string for the resolver software in use on the system, for example; `RES-2.1'" ::= { dnsResConfig 1 } dnsResConfigService OBJECT-TYPE SYNTAX INTEGER { recursiveOnly(1), iterativeOnly(2), recursiveAndIterative(3) } MAX-ACCESS read-only STATUS current DESCRIPTION "Kind of DNS resolution service provided: recursiveOnly(1) indicates a stub resolver. iterativeOnly(2) indicates a normal full service resolver. recursiveAndIterative(3) indicates a full-service resolver which performs a mix of recursive and iterative queries." ::= { dnsResConfig 2 } dnsResConfigMaxCnames OBJECT-TYPE SYNTAX INTEGER (0..2147483647) MAX-ACCESS read-write Austein & Saperia [Page 6]
RFC 1612 DNS Resolver MIB May 1994 STATUS current DESCRIPTION "Limit on how many CNAMEs the resolver should allow before deciding that there's a CNAME loop. Zero means that resolver has no explicit CNAME limit." REFERENCE "RFC-1035 section 7.1." ::= { dnsResConfig 3 } -- DNS Resolver Safety Belt Table dnsResConfigSbeltTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResConfigSbeltEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Table of safety belt information used by the resolver when it hasn't got any better idea of where to send a query, such as when the resolver is booting or is a stub resolver." ::= { dnsResConfig 4 } dnsResConfigSbeltEntry OBJECT-TYPE SYNTAX DnsResConfigSbeltEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry in the resolver's Sbelt table. Rows may be created or deleted at any time by the DNS resolver and by SNMP SET requests. Whether the values changed via SNMP are saved in stable storage across `reset' operations is implementation-specific." INDEX { dnsResConfigSbeltAddr, dnsResConfigSbeltSubTree, dnsResConfigSbeltClass } ::= { dnsResConfigSbeltTable 1 } DnsResConfigSbeltEntry ::= SEQUENCE { dnsResConfigSbeltAddr IpAddress, dnsResConfigSbeltName DnsName, dnsResConfigSbeltRecursion INTEGER, dnsResConfigSbeltPref INTEGER, dnsResConfigSbeltSubTree Austein & Saperia [Page 7]
RFC 1612 DNS Resolver MIB May 1994 DnsNameAsIndex, dnsResConfigSbeltClass DnsClass, dnsResConfigSbeltStatus RowStatus } dnsResConfigSbeltAddr OBJECT-TYPE SYNTAX IpAddress MAX-ACCESS not-accessible STATUS current DESCRIPTION "The IP address of the Sbelt name server identified by this row of the table." ::= { dnsResConfigSbeltEntry 1 } dnsResConfigSbeltName OBJECT-TYPE SYNTAX DnsName MAX-ACCESS read-create STATUS current DESCRIPTION "The DNS name of a Sbelt nameserver identified by this row of the table. A zero-length string indicates that the name is not known by the resolver." ::= { dnsResConfigSbeltEntry 2 } dnsResConfigSbeltRecursion OBJECT-TYPE SYNTAX INTEGER { iterative(1), recursive(2), recursiveAndIterative(3) } MAX-ACCESS read-create STATUS current DESCRIPTION "Kind of queries resolver will be sending to the name server identified in this row of the table: iterative(1) indicates that resolver will be directing iterative queries to this name server (RD bit turned off). recursive(2) indicates that resolver will be directing recursive queries to this name server (RD bit turned on). recursiveAndIterative(3) indicates that the resolver will be directing both recursive and iterative queries to the server identified in this row of the table." ::= { dnsResConfigSbeltEntry 3 } Austein & Saperia [Page 8]
RFC 1612 DNS Resolver MIB May 1994 dnsResConfigSbeltPref OBJECT-TYPE SYNTAX INTEGER (0..2147483647) MAX-ACCESS read-create STATUS current DESCRIPTION "This value identifies the preference for the name server identified in this row of the table. The lower the value, the more desirable the resolver considers this server." ::= { dnsResConfigSbeltEntry 4 } dnsResConfigSbeltSubTree OBJECT-TYPE SYNTAX DnsNameAsIndex MAX-ACCESS not-accessible STATUS current DESCRIPTION "Queries sent to the name server identified by this row of the table are limited to those for names in the name subtree identified by this variable. If no such limitation applies, the value of this variable is the name of the root domain (a DNS name consisting of a single zero octet)." ::= { dnsResConfigSbeltEntry 5 } dnsResConfigSbeltClass OBJECT-TYPE SYNTAX DnsClass MAX-ACCESS not-accessible STATUS current DESCRIPTION "The class of DNS queries that will be sent to the server identified by this row of the table." ::= { dnsResConfigSbeltEntry 6 } dnsResConfigSbeltStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "Row status column for this row of the Sbelt table." ::= { dnsResConfigSbeltEntry 7 } dnsResConfigUpTime OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "If the resolver has a persistent state (e.g., a process), this value will be the time elapsed since it Austein & Saperia [Page 9]
RFC 1612 DNS Resolver MIB May 1994 started. For software without persistant state, this value will be 0." ::= { dnsResConfig 5 } dnsResConfigResetTime OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "If the resolver has a persistent state (e.g., a process) and supports a `reset' operation (e.g., can be told to re-read configuration files), this value will be the time elapsed since the last time the resolver was `reset.' For software that does not have persistence or does not support a `reset' operation, this value will be zero." ::= { dnsResConfig 6 } dnsResConfigReset OBJECT-TYPE SYNTAX INTEGER { other(1), reset(2), initializing(3), running(4) } MAX-ACCESS read-write STATUS current DESCRIPTION "Status/action object to reinitialize any persistant resolver state. When set to reset(2), any persistant resolver state (such as a process) is reinitialized as if the resolver had just been started. This value will never be returned by a read operation. When read, one of the following values will be returned: other(1) - resolver in some unknown state; initializing(3) - resolver (re)initializing; running(4) - resolver currently running." ::= { dnsResConfig 7 } -- Resolver Counters Group -- Resolver Counter Table dnsResCounterByOpcodeTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResCounterByOpcodeEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Table of the current count of resolver queries and Austein & Saperia [Page 10]
RFC 1612 DNS Resolver MIB May 1994 answers." ::= { dnsResCounter 3 } dnsResCounterByOpcodeEntry OBJECT-TYPE SYNTAX DnsResCounterByOpcodeEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Entry in the resolver counter table. Entries are indexed by DNS OpCode." INDEX { dnsResCounterByOpcodeCode } ::= { dnsResCounterByOpcodeTable 1 } DnsResCounterByOpcodeEntry ::= SEQUENCE { dnsResCounterByOpcodeCode DnsOpCode, dnsResCounterByOpcodeQueries Counter32, dnsResCounterByOpcodeResponses Counter32 } dnsResCounterByOpcodeCode OBJECT-TYPE SYNTAX DnsOpCode MAX-ACCESS not-accessible STATUS current DESCRIPTION "The index to this table. The OpCodes that have already been defined are found in RFC-1035." REFERENCE "RFC-1035 section 4.1.1." ::= { dnsResCounterByOpcodeEntry 1 } dnsResCounterByOpcodeQueries OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Total number of queries that have sent out by the resolver since initialization for the OpCode which is the index to this row of the table." ::= { dnsResCounterByOpcodeEntry 2 } dnsResCounterByOpcodeResponses OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current Austein & Saperia [Page 11]
RFC 1612 DNS Resolver MIB May 1994 DESCRIPTION "Total number of responses that have been received by the resolver since initialization for the OpCode which is the index to this row of the table." ::= { dnsResCounterByOpcodeEntry 3 } -- Resolver Response Code Counter Table dnsResCounterByRcodeTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResCounterByRcodeEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Table of the current count of responses to resolver queries." ::= { dnsResCounter 4 } dnsResCounterByRcodeEntry OBJECT-TYPE SYNTAX DnsResCounterByRcodeEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Entry in the resolver response table. Entries are indexed by DNS response code." INDEX { dnsResCounterByRcodeCode } ::= { dnsResCounterByRcodeTable 1 } DnsResCounterByRcodeEntry ::= SEQUENCE { dnsResCounterByRcodeCode DnsRespCode, dnsResCounterByRcodeResponses Counter32 } dnsResCounterByRcodeCode OBJECT-TYPE SYNTAX DnsRespCode MAX-ACCESS not-accessible STATUS current DESCRIPTION "The index to this table. The Response Codes that have already been defined are found in RFC-1035." REFERENCE "RFC-1035 section 4.1.1." ::= { dnsResCounterByRcodeEntry 1 } Austein & Saperia [Page 12]
RFC 1612 DNS Resolver MIB May 1994 dnsResCounterByRcodeResponses OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of responses the resolver has received for the response code value which identifies this row of the table." ::= { dnsResCounterByRcodeEntry 2 } -- Additional DNS Resolver Counter Objects dnsResCounterNonAuthDataResps OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of requests made by the resolver for which a non-authoritative answer (cached data) was received." ::= { dnsResCounter 5 } dnsResCounterNonAuthNoDataResps OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of requests made by the resolver for which a non-authoritative answer - no such data response (empty answer) was received." ::= { dnsResCounter 6 } dnsResCounterMartians OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of responses received which were received from servers that the resolver does not think it asked." ::= { dnsResCounter 7 } dnsResCounterRecdResponses OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of responses received to all queries." ::= { dnsResCounter 8 } Austein & Saperia [Page 13]
RFC 1612 DNS Resolver MIB May 1994 dnsResCounterUnparseResps OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of responses received which were unparseable." ::= { dnsResCounter 9 } dnsResCounterFallbacks OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of times the resolver had to fall back to its seat belt information." ::= { dnsResCounter 10 } -- Lame Delegation Group dnsResLameDelegationOverflows OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of times the resolver attempted to add an entry to the Lame Delegation table but was unable to for some reason such as space constraints." ::= { dnsResLameDelegation 1 } -- Lame Delegation Table dnsResLameDelegationTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResLameDelegationEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Table of name servers returning lame delegations. A lame delegation has occured when a parent zone delegates authority for a child zone to a server that appears not to think that it is authoritative for the child zone in question." ::= { dnsResLameDelegation 2 } dnsResLameDelegationEntry OBJECT-TYPE SYNTAX DnsResLameDelegationEntry MAX-ACCESS not-accessible Austein & Saperia [Page 14]
RFC 1612 DNS Resolver MIB May 1994 STATUS current DESCRIPTION "Entry in lame delegation table. Only the resolver may create rows in this table. SNMP SET requests may be used to delete rows." INDEX { dnsResLameDelegationSource, dnsResLameDelegationName, dnsResLameDelegationClass } ::= { dnsResLameDelegationTable 1 } DnsResLameDelegationEntry ::= SEQUENCE { dnsResLameDelegationSource IpAddress, dnsResLameDelegationName DnsNameAsIndex, dnsResLameDelegationClass DnsClass, dnsResLameDelegationCounts Counter32, dnsResLameDelegationStatus RowStatus } dnsResLameDelegationSource OBJECT-TYPE SYNTAX IpAddress MAX-ACCESS not-accessible STATUS current DESCRIPTION "Source of lame delegation." ::= { dnsResLameDelegationEntry 1 } dnsResLameDelegationName OBJECT-TYPE SYNTAX DnsNameAsIndex MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS name for which lame delegation was received." ::= { dnsResLameDelegationEntry 2 } dnsResLameDelegationClass OBJECT-TYPE SYNTAX DnsClass MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS class of received lame delegation." ::= { dnsResLameDelegationEntry 3 } Austein & Saperia [Page 15]
RFC 1612 DNS Resolver MIB May 1994 dnsResLameDelegationCounts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "How many times this lame delegation has been received." ::= { dnsResLameDelegationEntry 4 } dnsResLameDelegationStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-write STATUS current DESCRIPTION "Status column for the lame delegation table. Since only the agent (DNS resolver) creates rows in this table, the only values that a manager may write to this variable are active(1) and destroy(6)." ::= { dnsResLameDelegationEntry 5 } -- Resolver Cache Group dnsResCacheStatus OBJECT-TYPE SYNTAX INTEGER { enabled(1), disabled(2), clear(3) } MAX-ACCESS read-write STATUS current DESCRIPTION "Status/action for the resolver's cache. enabled(1) means that the use of the cache is allowed. Query operations can return this state. disabled(2) means that the cache is not being used. Query operations can return this state. Setting this variable to clear(3) deletes the entire contents of the resolver's cache, but does not otherwise change the resolver's state. The status will retain its previous value from before the clear operation (i.e., enabled(1) or disabled(2)). The value of clear(3) can NOT be returned by a query operation." ::= { dnsResCache 1 } dnsResCacheMaxTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-write STATUS current DESCRIPTION Austein & Saperia [Page 16]
RFC 1612 DNS Resolver MIB May 1994 "Maximum Time-To-Live for RRs in this cache. If the resolver does not implement a TTL ceiling, the value of this field should be zero." ::= { dnsResCache 2 } dnsResCacheGoodCaches OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of RRs the resolver has cached successfully." ::= { dnsResCache 3 } dnsResCacheBadCaches OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of RRs the resolver has refused to cache because they appear to be dangerous or irrelevant. E.g., RRs with suspiciously high TTLs, unsolicited root information, or that just don't appear to be relevant to the question the resolver asked." ::= { dnsResCache 4 } -- Resolver Cache Table dnsResCacheRRTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResCacheRREntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "This table contains information about all the resource records currently in the resolver's cache." ::= { dnsResCache 5 } dnsResCacheRREntry OBJECT-TYPE SYNTAX DnsResCacheRREntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry in the resolvers's cache. Rows may be created only by the resolver. SNMP SET requests may be used to delete rows." INDEX { dnsResCacheRRName, dnsResCacheRRClass, dnsResCacheRRType, dnsResCacheRRIndex } Austein & Saperia [Page 17]
RFC 1612 DNS Resolver MIB May 1994 ::= { dnsResCacheRRTable 1 } DnsResCacheRREntry ::= SEQUENCE { dnsResCacheRRName DnsNameAsIndex, dnsResCacheRRClass DnsClass, dnsResCacheRRType DnsType, dnsResCacheRRTTL DnsTime, dnsResCacheRRElapsedTTL DnsTime, dnsResCacheRRSource IpAddress, dnsResCacheRRData OCTET STRING, dnsResCacheRRStatus RowStatus, dnsResCacheRRIndex Integer32, dnsResCacheRRPrettyName DnsName } dnsResCacheRRName OBJECT-TYPE SYNTAX DnsNameAsIndex MAX-ACCESS not-accessible STATUS current DESCRIPTION "Owner name of the Resource Record in the cache which is identified in this row of the table. As described in RFC-1034, the owner of the record is the domain name were the RR is found." REFERENCE "RFC-1034 section 3.6." ::= { dnsResCacheRREntry 1 } dnsResCacheRRClass OBJECT-TYPE SYNTAX DnsClass MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS class of the Resource Record in the cache which is identified in this row of the table." ::= { dnsResCacheRREntry 2 } Austein & Saperia [Page 18]
RFC 1612 DNS Resolver MIB May 1994 dnsResCacheRRType OBJECT-TYPE SYNTAX DnsType MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS type of the Resource Record in the cache which is identified in this row of the table." ::= { dnsResCacheRREntry 3 } dnsResCacheRRTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "Time-To-Live of RR in DNS cache. This is the initial TTL value which was received with the RR when it was originally received." ::= { dnsResCacheRREntry 4 } dnsResCacheRRElapsedTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "Elapsed seconds since RR was received." ::= { dnsResCacheRREntry 5 } dnsResCacheRRSource OBJECT-TYPE SYNTAX IpAddress MAX-ACCESS read-only STATUS current DESCRIPTION "Host from which RR was received, 0.0.0.0 if unknown." ::= { dnsResCacheRREntry 6 } dnsResCacheRRData OBJECT-TYPE SYNTAX OCTET STRING MAX-ACCESS read-only STATUS current DESCRIPTION "RDATA portion of a cached RR. The value is in the format defined for the particular DNS class and type of the resource record." REFERENCE "RFC-1035 section 3.2.1." ::= { dnsResCacheRREntry 7 } Austein & Saperia [Page 19]
RFC 1612 DNS Resolver MIB May 1994 dnsResCacheRRStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-write STATUS current DESCRIPTION "Status column for the resolver cache table. Since only the agent (DNS resolver) creates rows in this table, the only values that a manager may write to this variable are active(1) and destroy(6)." ::= { dnsResCacheRREntry 8 } dnsResCacheRRIndex OBJECT-TYPE SYNTAX Integer32 MAX-ACCESS not-accessible STATUS current DESCRIPTION "A value which makes entries in the table unique when the other index values (dnsResCacheRRName, dnsResCacheRRClass, and dnsResCacheRRType) do not provide a unique index." ::= { dnsResCacheRREntry 9 } dnsResCacheRRPrettyName OBJECT-TYPE SYNTAX DnsName MAX-ACCESS read-only STATUS current DESCRIPTION "Name of the RR at this row in the table. This is identical to the dnsResCacheRRName variable, except that character case is preserved in this variable, per DNS conventions." REFERENCE "RFC-1035 section 2.3.3." ::= { dnsResCacheRREntry 10 } -- Resolver Negative Cache Group dnsResNCacheStatus OBJECT-TYPE SYNTAX INTEGER { enabled(1), disabled(2), clear(3) } MAX-ACCESS read-write STATUS current DESCRIPTION "Status/action for the resolver's negative response cache. enabled(1) means that the use of the negative response cache is allowed. Query operations can return this state. Austein & Saperia [Page 20]
RFC 1612 DNS Resolver MIB May 1994 disabled(2) means that the negative response cache is not being used. Query operations can return this state. Setting this variable to clear(3) deletes the entire contents of the resolver's negative response cache. The status will retain its previous value from before the clear operation (i.e., enabled(1) or disabled(2)). The value of clear(3) can NOT be returned by a query operation." ::= { dnsResNCache 1 } dnsResNCacheMaxTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-write STATUS current DESCRIPTION "Maximum Time-To-Live for cached authoritative errors. If the resolver does not implement a TTL ceiling, the value of this field should be zero." ::= { dnsResNCache 2 } dnsResNCacheGoodNCaches OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of authoritative errors the resolver has cached successfully." ::= { dnsResNCache 3 } dnsResNCacheBadNCaches OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of authoritative errors the resolver would have liked to cache but was unable to because the appropriate SOA RR was not supplied or looked suspicious." REFERENCE "RFC-1034 section 4.3.4." ::= { dnsResNCache 4 } -- Resolver Negative Cache Table dnsResNCacheErrTable OBJECT-TYPE SYNTAX SEQUENCE OF DnsResNCacheErrEntry MAX-ACCESS not-accessible STATUS current Austein & Saperia [Page 21]
RFC 1612 DNS Resolver MIB May 1994 DESCRIPTION "The resolver's negative response cache. This table contains information about authoritative errors that have been cached by the resolver." ::= { dnsResNCache 5 } dnsResNCacheErrEntry OBJECT-TYPE SYNTAX DnsResNCacheErrEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry in the resolver's negative response cache table. Only the resolver can create rows. SNMP SET requests may be used to delete rows." INDEX { dnsResNCacheErrQName, dnsResNCacheErrQClass, dnsResNCacheErrQType, dnsResNCacheErrIndex } ::= { dnsResNCacheErrTable 1 } DnsResNCacheErrEntry ::= SEQUENCE { dnsResNCacheErrQName DnsNameAsIndex, dnsResNCacheErrQClass DnsQClass, dnsResNCacheErrQType DnsQType, dnsResNCacheErrTTL DnsTime, dnsResNCacheErrElapsedTTL DnsTime, dnsResNCacheErrSource IpAddress, dnsResNCacheErrCode INTEGER, dnsResNCacheErrStatus RowStatus, dnsResNCacheErrIndex Integer32, dnsResNCacheErrPrettyName DnsName } dnsResNCacheErrQName OBJECT-TYPE SYNTAX DnsNameAsIndex MAX-ACCESS not-accessible STATUS current Austein & Saperia [Page 22]
RFC 1612 DNS Resolver MIB May 1994 DESCRIPTION "QNAME associated with a cached authoritative error." REFERENCE "RFC-1034 section 3.7.1." ::= { dnsResNCacheErrEntry 1 } dnsResNCacheErrQClass OBJECT-TYPE SYNTAX DnsQClass MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS QCLASS associated with a cached authoritative error." ::= { dnsResNCacheErrEntry 2 } dnsResNCacheErrQType OBJECT-TYPE SYNTAX DnsQType MAX-ACCESS not-accessible STATUS current DESCRIPTION "DNS QTYPE associated with a cached authoritative error." ::= { dnsResNCacheErrEntry 3 } dnsResNCacheErrTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "Time-To-Live of a cached authoritative error at the time of the error, it should not be decremented by the number of seconds since it was received. This should be the TTL as copied from the MINIMUM field of the SOA that accompanied the authoritative error, or a smaller value if the resolver implements a ceiling on negative response cache TTLs." REFERENCE "RFC-1034 section 4.3.4." ::= { dnsResNCacheErrEntry 4 } dnsResNCacheErrElapsedTTL OBJECT-TYPE SYNTAX DnsTime MAX-ACCESS read-only STATUS current DESCRIPTION "Elapsed seconds since authoritative error was received." ::= { dnsResNCacheErrEntry 5 } Austein & Saperia [Page 23]
RFC 1612 DNS Resolver MIB May 1994 dnsResNCacheErrSource OBJECT-TYPE SYNTAX IpAddress MAX-ACCESS read-only STATUS current DESCRIPTION "Host which sent the authoritative error, 0.0.0.0 if unknown." ::= { dnsResNCacheErrEntry 6 } dnsResNCacheErrCode OBJECT-TYPE SYNTAX INTEGER { nonexistantName(1), noData(2), other(3) } MAX-ACCESS read-only STATUS current DESCRIPTION "The authoritative error that has been cached: nonexistantName(1) indicates an authoritative name error (RCODE = 3). noData(2) indicates an authoritative response with no error (RCODE = 0) and no relevant data. other(3) indicates some other cached authoritative error. At present, no such errors are known to exist." ::= { dnsResNCacheErrEntry 7 } dnsResNCacheErrStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-write STATUS current DESCRIPTION "Status column for the resolver negative response cache table. Since only the agent (DNS resolver) creates rows in this table, the only values that a manager may write to this variable are active(1) and destroy(6)." ::= { dnsResNCacheErrEntry 8 } dnsResNCacheErrIndex OBJECT-TYPE SYNTAX Integer32 MAX-ACCESS read-only STATUS current DESCRIPTION "A value which makes entries in the table unique when the other index values (dnsResNCacheErrQName, dnsResNCacheErrQClass, and dnsResNCacheErrQType) do not provide a unique index." ::= { dnsResNCacheErrEntry 9 } Austein & Saperia [Page 24]
RFC 1612 DNS Resolver MIB May 1994 dnsResNCacheErrPrettyName OBJECT-TYPE SYNTAX DnsName MAX-ACCESS read-only STATUS current DESCRIPTION "QNAME associated with this row in the table. This is identical to the dnsResNCacheErrQName variable, except that character case is preserved in this variable, per DNS conventions." REFERENCE "RFC-1035 section 2.3.3." ::= { dnsResNCacheErrEntry 10 } -- Resolver Optional Counters Group dnsResOptCounterReferals OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of responses which were received from servers redirecting query to another server." ::= { dnsResOptCounter 1 } dnsResOptCounterRetrans OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number requests retransmitted for all reasons." ::= { dnsResOptCounter 2 } dnsResOptCounterNoResponses OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of queries that were retransmitted because of no response." ::= { dnsResOptCounter 3 } dnsResOptCounterRootRetrans OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of queries that were retransmitted that were to Austein & Saperia [Page 25]
RFC 1612 DNS Resolver MIB May 1994 root servers." ::= { dnsResOptCounter 4 } dnsResOptCounterInternals OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of requests internally generated by the resolver." ::= { dnsResOptCounter 5 } dnsResOptCounterInternalTimeOuts OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "Number of requests internally generated which timed out." ::= { dnsResOptCounter 6 } -- SNMPv2 groups. dnsResMIBGroups OBJECT IDENTIFIER ::= { dnsResMIB 2 } dnsResConfigGroup OBJECT-GROUP OBJECTS { dnsResConfigImplementIdent, dnsResConfigService, dnsResConfigMaxCnames, dnsResConfigSbeltAddr, dnsResConfigSbeltName, dnsResConfigSbeltRecursion, dnsResConfigSbeltPref, dnsResConfigSbeltSubTree, dnsResConfigSbeltClass, dnsResConfigSbeltStatus, dnsResConfigUpTime, dnsResConfigResetTime } STATUS current DESCRIPTION "A collection of objects providing basic configuration information for a DNS resolver implementation." ::= { dnsResMIBGroups 1 } dnsResCounterGroup OBJECT-GROUP OBJECTS { dnsResCounterByOpcodeCode, dnsResCounterByOpcodeQueries, Austein & Saperia [Page 26]
RFC 1612 DNS Resolver MIB May 1994 dnsResCounterByOpcodeResponses, dnsResCounterByRcodeCode, dnsResCounterByRcodeResponses, dnsResCounterNonAuthDataResps, dnsResCounterNonAuthNoDataResps, dnsResCounterMartians, dnsResCounterRecdResponses, dnsResCounterUnparseResps, dnsResCounterFallbacks } STATUS current DESCRIPTION "A collection of objects providing basic instrumentation of a DNS resolver implementation." ::= { dnsResMIBGroups 2 } dnsResLameDelegationGroup OBJECT-GROUP OBJECTS { dnsResLameDelegationOverflows, dnsResLameDelegationSource, dnsResLameDelegationName, dnsResLameDelegationClass, dnsResLameDelegationCounts, dnsResLameDelegationStatus } STATUS current DESCRIPTION "A collection of objects providing instrumentation of `lame delegation' failures." ::= { dnsResMIBGroups 3 } dnsResCacheGroup OBJECT-GROUP OBJECTS { dnsResCacheStatus, dnsResCacheMaxTTL, dnsResCacheGoodCaches, dnsResCacheBadCaches, dnsResCacheRRName, dnsResCacheRRClass, dnsResCacheRRType, dnsResCacheRRTTL, dnsResCacheRRElapsedTTL, dnsResCacheRRSource, dnsResCacheRRData, dnsResCacheRRStatus, dnsResCacheRRIndex, dnsResCacheRRPrettyName } STATUS current DESCRIPTION "A collection of objects providing access to and control of a DNS resolver's cache." Austein & Saperia [Page 27]
RFC 1612 DNS Resolver MIB May 1994 ::= { dnsResMIBGroups 4 } dnsResNCacheGroup OBJECT-GROUP OBJECTS { dnsResNCacheStatus, dnsResNCacheMaxTTL, dnsResNCacheGoodNCaches, dnsResNCacheBadNCaches, dnsResNCacheErrQName, dnsResNCacheErrQClass, dnsResNCacheErrQType, dnsResNCacheErrTTL, dnsResNCacheErrElapsedTTL, dnsResNCacheErrSource, dnsResNCacheErrCode, dnsResNCacheErrStatus, dnsResNCacheErrIndex, dnsResNCacheErrPrettyName } STATUS current DESCRIPTION "A collection of objects providing access to and control of a DNS resolver's negative response cache." ::= { dnsResMIBGroups 5 } dnsResOptCounterGroup OBJECT-GROUP OBJECTS { dnsResOptCounterReferals, dnsResOptCounterRetrans, dnsResOptCounterNoResponses, dnsResOptCounterRootRetrans, dnsResOptCounterInternals, dnsResOptCounterInternalTimeOuts } STATUS current DESCRIPTION "A collection of objects providing further instrumentation applicable to many but not all DNS resolvers." ::= { dnsResMIBGroups 6 } -- Compliances. dnsResMIBCompliances OBJECT IDENTIFIER ::= { dnsResMIB 3 } dnsResMIBCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for agents implementing the DNS resolver MIB extensions." MODULE -- This MIB module Austein & Saperia [Page 28]
RFC 1612 DNS Resolver MIB May 1994 MANDATORY-GROUPS { dnsResConfigGroup, dnsResCounterGroup } GROUP dnsResCacheGroup DESCRIPTION "The resolver cache group is mandatory for resolvers that implement a cache." GROUP dnsResNCacheGroup DESCRIPTION "The resolver negative cache group is mandatory for resolvers that implement a negative response cache." GROUP dnsResLameDelegationGroup DESCRIPTION "The lame delegation group is unconditionally optional." GROUP dnsResOptCounterGroup DESCRIPTION "The optional counters group is unconditionally optional." OBJECT dnsResConfigMaxCnames MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResConfigSbeltName MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResConfigSbeltRecursion MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResConfigSbeltPref MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResConfigReset MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResCacheStatus MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResCacheMaxTTL MIN-ACCESS read-only DESCRIPTION "This object need not be writable." OBJECT dnsResNCacheStatus MIN-ACCESS read-only DESCRIPTION "This object need not be writable." Austein & Saperia [Page 29]
RFC 1612 DNS Resolver MIB May 1994 OBJECT dnsResNCacheMaxTTL MIN-ACCESS read-only DESCRIPTION "This object need not be writable." ::= { dnsResMIBCompliances 1 } END 5. Acknowledgements This document is the result of work undertaken the by DNS working group. The authors would particularly like to thank the following people for their contributions to this document: Philip Almquist, Frank Kastenholz (FTP Software), Joe Peck (DEC), Dave Perkins (SynOptics), Win Treese (DEC), and Mimi Zohar (IBM). 6. References [1] Mockapetris, P., "Domain Names -- Concepts and Facilities", STD 13, RFC 1034, USC/Information Sciences Institute, November 1987. [2] Mockapetris, P., "Domain Names -- Implementation and Specification", STD 13, RFC 1035, USC/Information Sciences Institute, November 1987. [3] Braden, R., Editor, "Requirements for Internet Hosts -- Application and Support, STD 3, RFC 1123, USC/Information Sciences Institute, October 1989. [4] Rose, M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based internets", STD 16, RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990. [5] McCloghrie, K., and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets", RFC 1156, Hughes LAN Systems, Performance Systems International, May 1990. [6] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network Management Protocol", STD 15, RFC 1157, SNMP Research, Performance Systems International, Performance Systems International, MIT Laboratory for Computer Science, May 1990. [7] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions", STD 16, RFC 1212, Performance Systems International, Hughes LAN Systems, March 1991. Austein & Saperia [Page 30]
RFC 1612 DNS Resolver MIB May 1994 [8] McCloghrie, K., and M. Rose, "Management Information Base for Network Management of TCP/IP-based internets: MIB-II", STD 17, RFC 1213, Hughes LAN Systems, Performance Systems International, March 1991. [9] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Structure of Management Information for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1442, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993. [10] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Textual Conventions for version 2 of the the Simple Network Management Protocol (SNMPv2)", RFC 1443, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993. [11] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Conformance Statements for version 2 of the the Simple Network Management Protocol (SNMPv2)", RFC 1444, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993. [12] Galvin, J., and K. McCloghrie, "Administrative Model for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1445, Trusted Information Systems, Hughes LAN Systems, April 1993. [13] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Protocol Operations for version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1448, SNMP Research, Inc., Hughes LAN Systems, Dover Beach Consulting, Inc., Carnegie Mellon University, April 1993. [14] "Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1)", International Organization for Standardization, International Standard 8824, December 1987. Austein & Saperia [Page 31]
RFC 1612 DNS Resolver MIB May 1994 7. Security Considerations Security issues are not discussed in this memo. 8. Authors' Addresses Rob Austein Epilogue Technology Corporation 268 Main Street, Suite 283 North Reading, MA 01864 USA Phone: +1-617-245-0804 Fax: +1-617-245-8122 EMail: sra@epilogue.com Jon Saperia Digital Equipment Corporation 110 Spit Brook Road ZKO1-3/H18 Nashua, NH 03062-2698 USA Phone: +1-603-881-0480 Fax: +1-603-881-0120 EMail: saperia@zko.dec.com Austein & Saperia [Page 32]