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DNS & NetworkingIETF RFC 1035 Section 4.1.1 / RFC 6895 / IANA DNS RCODE Registry✓ 빠른 조회 매트릭스 표 (6 개 항목) • KO

DNS 응답 코드 (RCODE) 표준 레퍼런스

NOERROR, NXDOMAIN, SERVFAIL, REFUSED 및 네트워크 장애 진단

CT
Curious-Techie Engineering Team검증된 작성자

Web Protocols & Security Architecture Research

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공식 기술 규격:RFC 9110(IETF)
검토자: Curious-Techie Architecture Peer Review Group

개요 및 범위

RFC 1035 및 RFC 6895 규격의 RCODE는 네임서버 질의 실패의 근본 원인을 식별하는 핵심 네트워크 진단 표준입니다.

표준 규격표 및 매트릭스

키워드, 상태 코드 또는 지시문 이름으로 실시간 검색

키 / 코드정의 및 세부사항GEO 시맨틱 계층표준 규격 및 참고
RCODE 0
NOERROR (RCODE 0)

No error condition; the query completed successfully and answer records may be present.

status: NOERROR
●NOERROR
↳DNS RCODE
↳RCODE 0
↳successful resolution
RFC 1035 §4.1.1

A NOERROR response with 0 answers (NODATA) indicates the domain exists, but has no records for the requested type (e.g. asking for AAAA on an IPv4-only site).

RCODE 1
FORMERR (RCODE 1)

Format Error; the name server was unable to interpret the query due to malformed packet syntax.

status: FORMERR
●FORMERR
↳DNS RCODE
↳RCODE 1
↳malformed query packet
RFC 1035 §4.1.1

Rare; occurs when custom client network code emits corrupted UDP DNS packets.

RCODE 2
SERVFAIL (RCODE 2)

Server Failure; the resolver was unable to process the query due to a problem with the authoritative nameservers.

status: SERVFAIL
●SERVFAIL
↳DNS RCODE
↳RCODE 2
↳nameserver failure or DNSSEC bogus
RFC 1035 §4.1.1

Common causes: authoritative nameservers unreachable, network timeouts, or DNSSEC cryptographic validation failure.

RCODE 3
NXDOMAIN (RCODE 3)

Non-Existent Domain; authoritative nameserver asserts that the requested domain name does not exist.

status: NXDOMAIN
●NXDOMAIN
↳DNS RCODE
↳RCODE 3
↳authoritative non-existence
RFC 1035 §4.1.1

Cached according to the minimum TTL in the SOA record; common for typos, expired domains, or missing subdomains.

RCODE 4
NOTIMP (RCODE 4)

Not Implemented; the name server does not support the requested query opcode.

status: NOTIMP
●NOTIMP
↳DNS RCODE
↳RCODE 4
↳unsupported query operation
RFC 1035 §4.1.1

Triggered when requesting obsolete or experimental DNS opcodes (e.g., IQUERY).

RCODE 5
REFUSED (RCODE 5)

Refused; the name server refuses to perform the specified operation for policy or security reasons.

status: REFUSED
●REFUSED
↳DNS RCODE
↳RCODE 5
↳access policy refusal
RFC 1035 §4.1.1

Occurs when asking a closed enterprise resolver for external recursive lookups (recursion disabled).

기술 예제 및 실행 코드

Inspecting DNS RCODE in Terminal

bash코드 복사
$ dig api.example.com
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 48210
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1

# Note status: NXDOMAIN indicates the domain was not found.
# If status was SERVFAIL, test without DNSSEC validation:
$ dig api.example.com +cdflag

The +cdflag (Checking Disabled) tells the resolver to bypass DNSSEC validation. If +cdflag succeeds, your DNSSEC keys are out of sync.

자주 묻는 질문 (FAQ)

표준 규격 Q&A

What is the difference between NXDOMAIN and NODATA?↓
NXDOMAIN (RCODE 3) means the domain itself does not exist. NODATA means the domain exists (status: NOERROR), but no records match the requested type (e.g. asking for AAAA when only A exists).
Authoritative Sourcing & Verification

References & Primary Sources

Every source below directly substantiates technical statements and protocol behaviors explained in DNS 응답 코드 (RCODE) 표준 레퍼런스. Curious-Techie prioritizes official Internet standards (IETF RFCs, W3C Recommendations, WHATWG specifications) and established security bodies (OWASP, NIST). Zero sponsored or secondary links.

  1. [1]IETFPrimary SpecificationRFC 1034 • Section 3 & 4
    Verified Primary Source
    RFC 1034: Domain Names — Concepts and Facilities
    Technical Claim Supported:

    Establishes the hierarchical distributed domain name space, authoritative name servers, root zone topology, and zone delegations.

    Source URI: https://datatracker.ietf.org/doc/html/rfc1034
  2. [2]IETFPrimary SpecificationRFC 1035 • Section 3.2 (Resource Records)
    Verified Primary Source
    RFC 1035: Domain Names — Implementation and Specification
    Technical Claim Supported:

    Defines standard DNS Resource Record wire structures (A, CNAME, MX, NS, PTR, SOA) and port 53 UDP/TCP protocol formats.

    Source URI: https://datatracker.ietf.org/doc/html/rfc1035
  3. [3]IETFPrimary SpecificationRFC 8484 • Section 3 & 4
    Verified Primary Source
    RFC 8484: DNS Queries over HTTPS (DoH)
    Technical Claim Supported:

    Standardizes encrypted DNS query transmission inside HTTP/2 and HTTP/3 HTTPS streams to prevent ISP eavesdropping and on-path manipulation.

    Source URI: https://datatracker.ietf.org/doc/html/rfc8484
Semantic Internal Links (GEO)

관련 기술 생태계 및 다음 학습 단계

Context: DNS & Internet Name Resolution

추천 관련 개발자 도구

100% 브라우저 메모리 실행
100% Client-Side→

DNS Lookup & Propagation Tool

Query A, AAAA, CNAME, MX, TXT, and CAA records across global recursive resolvers.

RDAP Standard→

WHOIS & RDAP Domain Intelligence

Inspect domain registration, authoritative nameservers, and expiration dates.

관련 기술 가이드

아키텍처 배경 및 RFC 표준
Ultimate Guide→

Ultimate Guide to Domain Name System (DNS)

Recursive resolvers, authoritative nameservers, DNSSEC validation, and DoH transport.

관련 기술 아티클

아키텍처 정의
What Is→

What Is the Domain Name System (DNS)?

Direct explanation of hierarchical domain resolution from root servers to zone files.

Comparison→

DNS vs DNS-over-HTTPS (DoH): Privacy & Security

Traditional UDP port 53 lookups compared to encrypted TLS-encapsulated DoH queries.

Troubleshooting→

Troubleshooting: DNS Returns NXDOMAIN Error

Diagnose missing records, propagation lag, and nameserver delegation failures.

관련 기술 질문

직접 답변 (AEO 핵심 요약)
Q&A

What Happens When a DNS TTL Expires?

→

Answer: When a DNS TTL expires, caching resolvers evict the record and must re-query the authoritative nameserver before responding to clients.

Q&A

Can a CNAME Record Point to an IP Address?

→

Answer: No, RFC 1034 requires CNAME records to point exclusively to another domain name, never to raw IPv4 or IPv6 addresses.

Q&A

Why Can't a CNAME Record Coexist With Other Records at the Zone Apex?

→

Answer: RFC 1034 requires that if a CNAME exists at a node, no other record data may exist there. Since a zone apex must have SOA and NS records, CNAME is prohibited.

실습형 진단 랩

대화형 실습 워크벤치
Interactive LabBeginner

DNS Resolution & Propagation Lab

Trace recursive queries from root servers, simulate TTL countdowns, and diagnose NXDOMAIN errors.

토픽 아키텍처 클러스터 탐색 →

다음 학습 단계

DNS Specs → Recursive Query Lab
엔지니어링 권장안

DNS Resolution & Propagation Lab

Trace authoritative resolution from the root servers down to the zone file in the visual DNS workbench.

다음 실습으로 이동 →DNS Topic Architecture Cluster→