• Skip to main content
  • Skip to search
  • Skip to select language
MDN Web Docs
  • References
    • Overview / Web Technology

      Web technology reference for developers

    • HTML

      Structure of content on the web

    • CSS

      Code used to describe document style

    • JavaScript

      General-purpose scripting language

    • HTTP

      Protocol for transmitting web resources

    • Web APIs

      Interfaces for building web applications

    • Web Extensions

      Developing extensions for web browsers

    • Accessibility

      Build web projects usable for all

    • Web Technology

      Web technology reference for developers

  • Learn
    • Overview / MDN Learning Area

      Learn web development

    • MDN Learning Area

      Learn web development

    • HTML

      Learn to structure web content with HTML

    • CSS

      Learn to style content using CSS

    • JavaScript

      Learn to run scripts in the browser

    • Accessibility

      Learn to make the web accessible to all

  • Plus
    • Overview

      A customized MDN experience

    • AI Help

      Get real-time assistance and support

    • Updates

      All browser compatibility updates at a glance

    • Documentation

      Learn how to use MDN Plus

    • FAQ

      Frequently asked questions about MDN Plus

  • Curriculum New
  • Blog
    • Playground

      Write, test and share your code

    • HTTP Observatory

      Scan a website for free

    • AI Help

      Get real-time assistance and support

  • Log in
  • Sign up for free
  1. 開発者向けのウェブ技術
  2. HTTP
  3. Reference
  4. ヘッダー
  5. NEL
    • English (US)
    • Deutsch
    • Português (do Brasil)
    • 中文 (简体)

このページはコミュニティーの尽力で英語から翻訳されました。MDN Web Docs コミュニティーについてもっと知り、仲間になるにはこちらから。

この記事では

  • 構文
  • 仕様書
  • 関連情報
  1. HTTP
  2. ガイド
  3. HTTP の概要
  4. HTTP の進化
  5. 典型的な HTTP セッション
  6. HTTP メッセージ
  7. MIME タイプ（IANA メディア種別）
  8. HTTP の圧縮
  9. HTTP キャッシュ
  10. HTTP 認証
  11. HTTP Cookie の使用
  12. HTTP のリダイレクト
  13. HTTP 条件付きリクエスト
  14. HTTP 範囲リクエスト
  15. コンテンツネゴシエーション
  16. HTTP/1.x のコネクション管理
  17. プロトコルのアップグレードの仕組み
  18. プロキシサーバーとトンネリング
  19. HTTP クライアントヒント
  20. HTTP セキュリティ
    1. 実践的なセキュリティ実装ガイド
    2. HTTP Observatory
    3. Permissions Policy Experimental
    4. コンテンツセキュリティポリシー (CSP)
    5. Cross-Origin Resource Policy (CORP)
    6. オリジン間リソース共有 (CORS)
    7. CORS エラー
      1. Reason: CORS disabled
      2. Reason: CORS header 'Access-Control-Allow-Origin' does not match 'xyz'
      3. Reason: CORS header 'Access-Control-Allow-Origin' missing
      4. Reason: CORS header 'Origin' cannot be added
      5. Reason: CORS preflight channel did not succeed
      6. Reason: CORS request did not succeed
      7. Reason: CORS request external redirect not allowed
      8. Reason: CORS request not HTTP
      9. Reason: Credential is not supported if the CORS header 'Access-Control-Allow-Origin' is '*'
      10. Reason: Did not find method in CORS header 'Access-Control-Allow-Methods'
      11. Reason: expected 'true' in CORS header 'Access-Control-Allow-Credentials'
      12. Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Headers'
      13. Reason: invalid token 'xyz' in CORS header 'Access-Control-Allow-Methods'
      14. Reason: missing token ‘xyz’ in CORS header ‘Access-Control-Allow-Headers’ from CORS preflight channel
      15. Reason: Multiple CORS header 'Access-Control-Allow-Origin' not allowed
  21. リファレンス
  22. HTTP ヘッダー
    1. Accept
    2. Accept-CH
    3. Accept-Encoding
    4. Accept-Language
    5. Accept-Patch
    6. Accept-Post
    7. Accept-Ranges
    8. Access-Control-Allow-Credentials
    9. Access-Control-Allow-Headers
    10. Access-Control-Allow-Methods
    11. Access-Control-Allow-Origin
    12. Access-Control-Expose-Headers
    13. Access-Control-Max-Age
    14. Access-Control-Request-Headers
    15. Access-Control-Request-Method
    16. Age
    17. Allow
    18. Alt-Svc
    19. Alt-Used
    20. Attribution-Reporting-Eligible Experimental
    21. Attribution-Reporting-Register-Source Experimental
    22. Attribution-Reporting-Register-Trigger Experimental
    23. Authorization
    24. Cache-Control
    25. Clear-Site-Data
    26. Connection
    27. Content-Digest
    28. Content-Disposition
    29. Content-DPR 非標準 非推奨;
    30. Content-Encoding
    31. Content-Language
    32. Content-Length
    33. Content-Location
    34. Content-Range
    35. Content-Security-Policy
    36. Content-Security-Policy-Report-Only
    37. Content-Type
    38. Cookie
    39. Critical-CH Experimental
    40. Cross-Origin-Embedder-Policy
    41. Cross-Origin-Opener-Policy
    42. Cross-Origin-Resource-Policy
    43. Date
    44. Device-Memory
    45. DNT 非標準 非推奨;
    46. Downlink Experimental
    47. DPR 非標準 非推奨;
    48. Early-Data Experimental
    49. ECT Experimental
    50. ETag
    51. Expect
    52. Expect-CT 非推奨;
    53. Expires
    54. Forwarded
    55. From
    56. Host
    57. If-Match
    58. If-Modified-Since
    59. If-None-Match
    60. If-Range
    61. If-Unmodified-Since
    62. Keep-Alive
    63. Last-Modified
    64. Link
    65. Location
    66. Max-Forwards
    67. NEL Experimental
    68. No-Vary-Search Experimental
    69. Observe-Browsing-Topics Experimental 非標準
    70. Origin
    71. Origin-Agent-Cluster Experimental
    72. Permissions-Policy Experimental
    73. Pragma 非推奨;
    74. Priority
    75. Proxy-Authenticate
    76. Proxy-Authorization
    77. Range
    78. Referer
    79. Referrer-Policy
    80. Refresh
    81. Report-To 非標準 非推奨;
    82. Reporting-Endpoints Experimental
    83. Repr-Digest
    84. Retry-After
    85. RTT Experimental
    86. Save-Data Experimental
    87. Sec-Browsing-Topics Experimental 非標準
    88. Sec-CH-Prefers-Color-Scheme Experimental
    89. Sec-CH-Prefers-Reduced-Motion Experimental
    90. Sec-CH-Prefers-Reduced-Transparency Experimental
    91. Sec-CH-UA Experimental
    92. Sec-CH-UA-Arch Experimental
    93. Sec-CH-UA-Bitness Experimental
    94. Sec-CH-UA-Form-Factors Experimental
    95. Sec-CH-UA-Full-Version 非推奨;
    96. Sec-CH-UA-Full-Version-List Experimental
    97. Sec-CH-UA-Mobile Experimental
    98. Sec-CH-UA-Model Experimental
    99. Sec-CH-UA-Platform Experimental
    100. Sec-CH-UA-Platform-Version Experimental
    101. Sec-CH-UA-WoW64 Experimental
    102. Sec-Fetch-Dest
    103. Sec-Fetch-Mode
    104. Sec-Fetch-Site
    105. Sec-Fetch-User
    106. Sec-GPC Experimental
    107. Sec-Purpose
    108. Sec-WebSocket-Accept
    109. Sec-WebSocket-Extensions
    110. Sec-WebSocket-Key
    111. Sec-WebSocket-Protocol
    112. Sec-WebSocket-Version
    113. Server
    114. Server-Timing
    115. Service-Worker
    116. Service-Worker-Allowed
    117. Service-Worker-Navigation-Preload
    118. Set-Cookie
    119. Set-Login Experimental
    120. SourceMap
    121. Speculation-Rules Experimental
    122. Strict-Transport-Security
    123. Supports-Loading-Mode Experimental
    124. TE
    125. Timing-Allow-Origin
    126. Tk 非標準 非推奨;
    127. Trailer
    128. Transfer-Encoding
    129. Upgrade
    130. Upgrade-Insecure-Requests
    131. User-Agent
    132. Vary
    133. Via
    134. Viewport-Width 非標準 非推奨;
    135. Want-Content-Digest
    136. Want-Repr-Digest
    137. Warning 非推奨;
    138. Width 非標準 非推奨;
    139. WWW-Authenticate
    140. X-Content-Type-Options
    141. X-DNS-Prefetch-Control 非標準
    142. X-Forwarded-For 非標準
    143. X-Forwarded-Host 非標準
    144. X-Forwarded-Proto 非標準
    145. X-Frame-Options
    146. X-Permitted-Cross-Domain-Policies 非標準
    147. X-Powered-By 非標準
    148. X-Robots-Tag 非標準
    149. X-XSS-Protection 非標準 非推奨;
  23. HTTP リクエストメソッド
    1. CONNECT
    2. DELETE
    3. GET
    4. HEAD
    5. OPTIONS
    6. PATCH
    7. POST
    8. PUT
    9. TRACE
  24. HTTP レスポンスステータスコード
    1. 100 Continue
    2. 101 Switching Protocols
    3. 102 Processing
    4. 103 Early Hints
    5. 200 OK
    6. 201 Created
    7. 202 Accepted
    8. 203 Non-Authoritative Information
    9. 204 No Content
    10. 205 Reset Content
    11. 206 Partial Content
    12. 207 Multi-Status
    13. 208 Already Reported
    14. 226 IM Used
    15. 300 Multiple Choices
    16. 301 Moved Permanently
    17. 302 Found
    18. 303 See Other
    19. 304 Not Modified
    20. 307 Temporary Redirect
    21. 308 Permanent Redirect
    22. 400 Bad Request
    23. 401 Unauthorized
    24. 402 Payment Required
    25. 403 Forbidden
    26. 404 Not Found
    27. 405 Method Not Allowed
    28. 406 Not Acceptable
    29. 407 Proxy Authentication Required
    30. 408 Request Timeout
    31. 409 Conflict
    32. 410 Gone
    33. 411 Length Required
    34. 412 Precondition Failed
    35. 413 Content Too Large
    36. 414 URI Too Long
    37. 415 Unsupported Media Type
    38. 416 Range Not Satisfiable
    39. 417 Expectation Failed
    40. 418 I'm a teapot
    41. 421 Misdirected Request
    42. 422 Unprocessable Content
    43. 423 Locked
    44. 424 Failed Dependency
    45. 425 Too Early
    46. 426 Upgrade Required
    47. 428 Precondition Required
    48. 429 Too Many Requests
    49. 431 Request Header Fields Too Large
    50. 451 Unavailable For Legal Reasons
    51. 500 Internal Server Error
    52. 501 Not Implemented
    53. 502 Bad Gateway
    54. 503 Service Unavailable
    55. 504 Gateway Timeout
    56. 505 HTTP Version Not Supported
    57. 506 Variant Also Negotiates
    58. 507 Insufficient Storage
    59. 508 Loop Detected
    60. 510 Not Extended
    61. 511 Network Authentication Required
  25. CSP ディレクティブ
    1. CSP: base-uri
    2. CSP: block-all-mixed-content 非推奨;
    3. CSP: child-src
    4. CSP: connect-src
    5. CSP: default-src
    6. CSP: fenced-frame-src Experimental
    7. CSP: font-src
    8. CSP: form-action
    9. CSP: frame-ancestors
    10. CSP: frame-src
    11. CSP: img-src
    12. CSP: manifest-src
    13. CSP: media-src
    14. CSP: object-src
    15. CSP: prefetch-src 非標準 非推奨;
    16. CSP: report-to
    17. CSP: report-uri 非推奨;
    18. CSP: require-trusted-types-for Experimental
    19. CSP: sandbox
    20. CSP: script-src
    21. CSP: script-src-attr
    22. CSP: script-src-elem
    23. CSP: style-src
    24. CSP: style-src-attr
    25. CSP: style-src-elem
    26. CSP: trusted-types Experimental
    27. CSP: upgrade-insecure-requests
    28. CSP: worker-src
  26. 機能ポリシーディレクティブ Experimental
    1. Feature-Policy: accelerometer Experimental
    2. Feature-Policy: ambient-light-sensor Experimental
    3. Permissions-Policy: attribution-reporting Experimental
    4. Feature-Policy: autoplay Experimental
    5. Permissions-Policy: bluetooth Experimental
    6. Permissions-Policy: browsing-topics Experimental 非標準
    7. Feature-Policy: camera Experimental
    8. Permissions-Policy: compute-pressure Experimental
    9. Permissions-Policy: cross-origin-isolated Experimental
    10. Feature-Policy: display-capture Experimental
    11. Feature-Policy: document-domain Experimental
    12. Feature-Policy: encrypted-media Experimental
    13. Feature-Policy: fullscreen Experimental
    14. Permissions-Policy: gamepad Experimental
    15. Feature-Policy: geolocation Experimental
    16. Permissions-Policy: gyroscope Experimental
    17. Permissions-Policy: hid Experimental
    18. Permissions-Policy: identity-credentials-get Experimental
    19. Permissions-Policy: idle-detection Experimental
    20. Permissions-Policy: local-fonts Experimental
    21. Permissions-Policy: magnetometer Experimental
    22. Feature-Policy: microphone Experimental
    23. Feature-Policy: midi Experimental
    24. Permissions-Policy: otp-credentials Experimental
    25. Feature-Policy: payment Experimental
    26. Permissions-Policy: picture-in-picture Experimental
    27. Permissions-Policy: publickey-credentials-create Experimental
    28. Permissions-Policy: publickey-credentials-get Experimental
    29. Feature-Policy: screen-wake-lock Experimental
    30. Permissions-Policy: serial Experimental
    31. Permissions-Policy: speaker-selection Experimental
    32. Permissions-Policy: storage-access Experimental
    33. Permissions-Policy: usb Experimental
    34. Feature-Policy: web-share Experimental
    35. Permissions-Policy: window-management Experimental
    36. Feature-Policy: xr-spatial-tracking Experimental
  27. HTTP のリソースと仕様書

この記事では

  • 構文
  • 仕様書
  • 関連情報

NEL

HTTP の NEL レスポンスヘッダーは、ネットワークリクエストログ記録を構成するために使用されます。

ヘッダー種別 レスポンスヘッダー
禁止ヘッダー名 いいえ

構文

NEL: { "report_to": "name_of_reporting_group", "max_age": 12345, "include_subdomains": false, "success_fraction": 0.0, "failure_fraction": 1.0 }

仕様書

仕様書
Network Error Logging

関連情報

  • Network Error Logging (NEL) の説明

Help improve MDN

Learn how to contribute.

This page was last modified on 2025年3月16日 by MDN contributors.

View this page on GitHub • Report a problem with this content
MDN logo

Your blueprint for a better internet.

  • MDN on Bluesky
  • MDN on Mastodon
  • MDN on X (formerly Twitter)
  • MDN on GitHub
  • MDN Blog RSS Feed

MDN

  • About
  • Blog
  • Careers
  • Advertise with us

Support

  • Product help
  • Report an issue

Our communities

  • MDN Community
  • MDN Forum
  • MDN Chat

Developers

  • Web Technologies
  • Learn Web Development
  • MDN Plus
  • Hacks Blog
  • Website Privacy Notice
  • Cookies
  • Legal
  • Community Participation Guidelines

Visit Mozilla Corporation’s not-for-profit parent, the Mozilla Foundation.
Portions of this content are ©1998–2025 by individual mozilla.org contributors. Content available under a Creative Commons license.