{"id":939,"date":"2026-10-15T00:00:00","date_gmt":"2026-10-14T15:00:00","guid":{"rendered":"https:\/\/quantumsea.net\/?p=939"},"modified":"2026-10-14T08:30:23","modified_gmt":"2026-10-13T23:30:23","slug":"qs-dns-negative-cache-20261014","status":"publish","type":"post","link":"https:\/\/quantumsea.net\/?p=939","title":{"rendered":"DNS\u306e\u30cd\u30ac\u30c6\u30a3\u30d6\u30ad\u30e3\u30c3\u30b7\u30e5\u3001\u300c\u540d\u524d\u304c\u306a\u3044\u300d\u3068\u300c\u30ec\u30b3\u30fc\u30c9\u304c\u306a\u3044\u300d\u306e\u9055\u3044"},"content":{"rendered":"<p>\u65b0\u3057\u3044\u30db\u30b9\u30c8\u540d\u3068IP\u30a2\u30c9\u30ec\u30b9\u3092DNS\u306b\u767b\u9332\u3057\u305f\u306e\u306b\u3001\u624b\u5143\u3067\u306f\u307e\u3060\u300c\u898b\u3064\u304b\u3089\u306a\u3044\u300d\u3068\u8fd4\u3063\u3066\u304f\u308b\u3002\u767b\u9332\u306b\u5931\u6557\u3057\u305f\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002DNS\u306f\u898b\u3064\u304b\u3063\u305f\u30c7\u30fc\u30bf\u3060\u3051\u3067\u306a\u304f\u3001<strong>\u5b58\u5728\u3057\u306a\u3044\u3068\u3044\u3046\u5fdc\u7b54\u3082\u671f\u9650\u4ed8\u304d\u3067\u4fdd\u5b58\u3059\u308b<\/strong>\u304b\u3089\u3067\u3059\u3002\u3053\u306e\u4ed5\u7d44\u307f\u3092\u30cd\u30ac\u30c6\u30a3\u30d6\u30ad\u30e3\u30c3\u30b7\u30e5\u3001\u307e\u305f\u306f\u5426\u5b9a\u5fdc\u7b54\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3068\u547c\u3073\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref1\">[1]<\/a><\/sup><\/p>\n<p>\u305f\u3060\u3057\u3001\u300c\u898b\u3064\u304b\u3089\u306a\u3044\u300d\u306b\u306f\u7a2e\u985e\u304c\u3042\u308a\u307e\u3059\u3002\u540d\u524d\u305d\u306e\u3082\u306e\u304c\u306a\u3044\u306e\u304b\u3001\u305d\u306e\u540d\u524d\u306b\u6b32\u3057\u3044\u7a2e\u985e\u306e\u30ec\u30b3\u30fc\u30c9\u304c\u306a\u3044\u306e\u304b\u3067\u3001\u4fdd\u5b58\u3057\u305f\u60c5\u5831\u3092\u4f7f\u3048\u308b\u7bc4\u56f2\u304c\u5909\u308f\u308a\u307e\u3059\u3002\u5fdc\u7b54\u306e\u610f\u5473\u3068\u6b8b\u308a\u6642\u9593\u3092\u5206\u3051\u3066\u898b\u308b\u3068\u3001DNS\u5909\u66f4\u5f8c\u306e\u5f85\u3061\u6642\u9593\u3092\u8aad\u307f\u89e3\u304d\u3084\u3059\u304f\u306a\u308a\u307e\u3059\u3002<\/p>\n<section class=\"influvetor-quick-summary\" aria-label=\"\u7c21\u5358\u306b\u307e\u3068\u3081\u308b\u3068\uff1f\">\n<p><strong>\u7c21\u5358\u306b\u307e\u3068\u3081\u308b\u3068\uff1f<\/strong><\/p>\n<ul>\n<li>NXDOMAIN\u306f\u540d\u524d\u306e\u4e0d\u5b58\u5728\u3001NODATA\u306f\u6307\u5b9a\u3057\u305f\u7a2e\u985e\u306e\u30c7\u30fc\u30bf\u306e\u4e0d\u5b58\u5728\u3092\u8868\u3057\u307e\u3059\u3002IPv6\u7528\u306eAAAA\u304c\u306a\u3044\u3053\u3068\u3060\u3051\u3067\u3001IPv4\u7528\u306eA\u307e\u3067\u306a\u3044\u3068\u306f\u5224\u65ad\u3067\u304d\u307e\u305b\u3093\u3002<\/li>\n<li>\u57fa\u672c\u306e\u5426\u5b9a\u5fdc\u7b54\u306e\u4fdd\u5b58\u6642\u9593\u306f\u3001SOA\u30ec\u30b3\u30fc\u30c9\u81ea\u8eab\u306eTTL\u3068SOA\u306eMINIMUM\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u5c0f\u3055\u3044\u65b9\u304b\u3089\u6c7a\u307e\u308a\u307e\u3059\u3002\u4fdd\u5b58\u6e08\u307f\u306e\u4e0d\u5728\u60c5\u5831\u306f\u3001\u65b0\u3057\u3044A\u30ec\u30b3\u30fc\u30c9\u3092\u8ffd\u52a0\u3057\u3066\u3082\u76f4\u3061\u306b\u306f\u6d88\u3048\u307e\u305b\u3093\u3002<\/li>\n<li>\u78ba\u8a8d\u3059\u308b\u306e\u306f\u5fdc\u7b54\u306e\u7a2e\u985e\u3001\u554f\u3044\u5408\u308f\u305b\u5148\u3001\u6b8b\u308aTTL\u3067\u3059\u3002\u89e3\u6c7a\u306b\u5931\u6557\u3057\u305fSERVFAIL\u3084\u3001\u969c\u5bb3\u6642\u306b\u671f\u9650\u5207\u308c\u60c5\u5831\u3092\u8fd4\u3059\u4ed5\u7d44\u307f\u306f\u3001\u901a\u5e38\u306e\u4e0d\u5b58\u5728\u5fdc\u7b54\u3068\u533a\u5225\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/section>\n<h2>\u300c\u540d\u524d\u304c\u306a\u3044\u300d\u3068\u300c\u305d\u306e\u7a2e\u985e\u306e\u30c7\u30fc\u30bf\u304c\u306a\u3044\u300d\u3092\u5206\u3051\u308b<\/h2>\n<p>DNS\u306e\u554f\u3044\u5408\u308f\u305b\u3067\u306f\u3001\u540d\u524d\u3060\u3051\u3067\u306a\u304f\u3001\u6b32\u3057\u3044\u30ec\u30b3\u30fc\u30c9\u306e\u7a2e\u985e\u3082\u6307\u5b9a\u3057\u307e\u3059\u3002A\u306fIPv4\u30a2\u30c9\u30ec\u30b9\u3001AAAA\u306fIPv6\u30a2\u30c9\u30ec\u30b9\u3092\u6c42\u3081\u308b\u3068\u304d\u306e\u7a2e\u985e\u3067\u3059\u3002\u3053\u3053\u3067\u306f\u4e00\u822c\u7684\u306a\u30a4\u30f3\u30bf\u30fc\u30cd\u30c3\u30c8\u7528\u306e\u30af\u30e9\u30b9IN\u3092\u524d\u63d0\u306b\u3001CNAME\u306a\u3069\u306e\u5225\u540d\u306e\u9023\u9396\u304c\u306a\u3044\u5834\u5408\u3092\u8003\u3048\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref1\">[1]<\/a><\/sup><\/p>\n<p><strong>NXDOMAIN<\/strong>\u306f\u3001\u305d\u306e\u540d\u524d\u304c\u5b58\u5728\u3057\u306a\u3044\u3068\u3044\u3046\u5fdc\u7b54\u3067\u3059\u3002\u4e00\u65b9\u3001<strong>NODATA<\/strong>\u306f\u540d\u524d\u306f\u3042\u308b\u3082\u306e\u306e\u3001\u6307\u5b9a\u3057\u305f\u7a2e\u985e\u306e\u30ec\u30b3\u30fc\u30c9\u304c\u306a\u3044\u3068\u3044\u3046\u610f\u5473\u3067\u3059\u3002NODATA\u5c02\u7528\u306e\u5fdc\u7b54\u30b3\u30fc\u30c9\u304c\u3042\u308b\u308f\u3051\u3067\u306f\u306a\u304f\u3001\u30b3\u30fc\u30c9\u306fNOERROR\u3067\u3001\u56de\u7b54\u6b04\u306b\u8a72\u5f53\u30c7\u30fc\u30bf\u304c\u306a\u3044\u3053\u3068\u306a\u3069\u304b\u3089\u5224\u65ad\u3057\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref1\">[1]<\/a><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<div style=\"width:720px;max-width:100%;margin:1.5em auto;overflow-x:auto;\">\n<table style=\"width:100%;min-width:620px;border-collapse:collapse;\">\n<caption>\u540c\u3058\u540d\u524d\u3092\u554f\u3044\u5408\u308f\u305b\u3066\u3082\u3001\u4e0d\u5728\u60c5\u5831\u306e\u7bc4\u56f2\u306f\u7570\u306a\u308b\uff08\u4ed5\u69d8\u306b\u57fa\u3065\u304f\u6574\u7406\uff09<\/caption>\n<thead>\n<tr>\n<th scope=\"col\">\u5fdc\u7b54<\/th>\n<th scope=\"col\">\u5206\u304b\u3063\u305f\u3053\u3068<\/th>\n<th scope=\"col\">\u5225\u306e\u7a2e\u985e\u3092\u554f\u3044\u5408\u308f\u305b\u308b\u3068\u304d<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>NXDOMAIN<\/td>\n<td>\u305d\u306e\u540d\u524d\u304c\u306a\u3044<\/td>\n<td>\u540c\u3058\u540d\u524d\u30fb\u30af\u30e9\u30b9\u306e\u5225\u306e\u7a2e\u985e\u306b\u3082\u3001\u305d\u306e\u4e0d\u5728\u60c5\u5831\u3092\u4f7f\u3048\u308b<\/td>\n<\/tr>\n<tr>\n<td>NODATA<\/td>\n<td>\u305d\u306e\u540d\u524d\u306b\u3001\u6307\u5b9a\u3057\u305f\u7a2e\u985e\u306e\u30c7\u30fc\u30bf\u304c\u306a\u3044<\/td>\n<td>AAAA\u304c\u306a\u3044\u3068\u3044\u3046\u60c5\u5831\u3060\u3051\u3067\u306f\u3001A\u304c\u3042\u308b\u304b\u306f\u5206\u304b\u3089\u306a\u3044<\/td>\n<\/tr>\n<tr>\n<td>SERVFAIL<\/td>\n<td>\u30b5\u30fc\u30d0\u30fc\u5074\u306e\u554f\u984c\u306a\u3069\u3067\u89e3\u6c7a\u3092\u5b8c\u4e86\u3067\u304d\u306a\u3044<\/td>\n<td>\u540d\u524d\u3084\u30ec\u30b3\u30fc\u30c9\u304c\u5b58\u5728\u3057\u306a\u3044\u3068\u7d50\u8ad6\u3065\u3051\u308b\u5fdc\u7b54\u3067\u306f\u306a\u3044<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>\u305f\u3068\u3048\u3070\u3001\u3042\u308b\u540d\u524d\u306bA\u3060\u3051\u304c\u767b\u9332\u3055\u308c\u3066\u3044\u308b\u306a\u3089\u3001AAAA\u3078\u306eNODATA\u3092\u4fdd\u5b58\u3057\u3066\u3044\u3066\u3082\u3001\u305d\u308c\u3060\u3051\u3092\u7406\u7531\u306bA\u306e\u554f\u3044\u5408\u308f\u305b\u3092\u5426\u5b9a\u3057\u3066\u306f\u3044\u3051\u307e\u305b\u3093\u3002\u307e\u305f\u3001NOERROR\u3067\u56de\u7b54\u6b04\u304c\u7a7a\u3068\u3044\u3046\u898b\u305f\u76ee\u3060\u3051\u3067\u3082\u5373\u65ad\u3067\u304d\u307e\u305b\u3093\u3002\u5225\u306e\u30cd\u30fc\u30e0\u30b5\u30fc\u30d0\u30fc\u3092\u6848\u5185\u3059\u308b\u5fdc\u7b54\u3082\u3042\u308b\u305f\u3081\u3001\u7ba1\u7406\u60c5\u5831\u3092\u8f09\u305b\u308bAuthority\u6b04\u306eSOA\u30ec\u30b3\u30fc\u30c9\u306a\u3069\u3001\u5fdc\u7b54\u5168\u4f53\u3092\u898b\u3066\u533a\u5225\u3057\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<h2>\u4e0d\u5b58\u5728\u306e\u671f\u9650\u306f\u3001SOA\u304c\u4f1d\u3048\u308b<\/h2>\n<p>\u5229\u7528\u8005\u306b\u4ee3\u308f\u3063\u3066DNS\u3092\u8abf\u3079\u308b\u30ea\u30be\u30eb\u30d0\u30fc\u306f\u3001\u53d7\u3051\u53d6\u3063\u305f\u5fdc\u7b54\u3092\u30ad\u30e3\u30c3\u30b7\u30e5\u3057\u3001\u540c\u3058\u554f\u3044\u5408\u308f\u305b\u306b\u518d\u5229\u7528\u3067\u304d\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u3063\u3066\u3001\u5b58\u5728\u3057\u306a\u3044\u540d\u524d\u3078\u306e\u554f\u3044\u5408\u308f\u305b\u3092\u7e70\u308a\u8fd4\u3059\u305f\u3073\u306b\u3001\u305d\u306e\u30be\u30fc\u30f3\u3092\u7ba1\u7406\u3059\u308b\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u307e\u3067\u8abf\u3079\u76f4\u3059\u8ca0\u62c5\u3092\u6e1b\u3089\u305b\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref1\">[1]<\/a><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<p>\u901a\u5e38\u306eA\u30ec\u30b3\u30fc\u30c9\u306a\u3089\u3001\u30c7\u30fc\u30bf\u3068\u4e00\u7dd2\u306bTTL\u3001\u3064\u307e\u308a\u4fdd\u5b58\u306b\u4f7f\u3048\u308b\u6642\u9593\u304c\u4ed8\u3044\u3066\u3044\u307e\u3059\u3002\u3068\u3053\u308d\u304c\u4e0d\u5b58\u5728\u306e\u5fdc\u7b54\u306b\u306f\u3001\u4fdd\u5b58\u5bfe\u8c61\u3068\u306a\u308bA\u30ec\u30b3\u30fc\u30c9\u81ea\u4f53\u304c\u3042\u308a\u307e\u305b\u3093\u3002\u305d\u3053\u3067\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u306f\u3001\u30be\u30fc\u30f3\u306e\u7ba1\u7406\u60c5\u5831\u3092\u8868\u3059SOA\u30ec\u30b3\u30fc\u30c9\u3092\u5fdc\u7b54\u306b\u6dfb\u3048\u3001\u305d\u306eTTL\u3067\u5426\u5b9a\u5fdc\u7b54\u306e\u671f\u9650\u3092\u4f1d\u3048\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<p>\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u304c\u5426\u5b9a\u5fdc\u7b54\u306b\u6dfb\u3048\u308bSOA\u306eTTL\u306f\u3001<strong>SOA\u30ec\u30b3\u30fc\u30c9\u81ea\u8eab\u306eTTL\u3068\u3001SOA\u5185\u306eMINIMUM\u30d5\u30a3\u30fc\u30eb\u30c9\u306e\u5c0f\u3055\u3044\u65b9<\/strong>\u306b\u8a2d\u5b9a\u3055\u308c\u307e\u3059\u3002\u305f\u3068\u3048\u3070\u524d\u8005\u304c900\u79d2\u3001\u5f8c\u8005\u304c300\u79d2\u306a\u3089\u3001\u57fa\u672c\u306e\u5426\u5b9a\u5fdc\u7b54TTL\u306f300\u79d2\u3067\u3059\u3002MINIMUM\u3068\u3044\u3046\u540d\u524d\u304b\u3089\u300c\u3059\u3079\u3066\u306e\u30ec\u30b3\u30fc\u30c9\u306b\u9069\u7528\u3059\u308b\u6700\u4f4eTTL\u300d\u3068\u53d7\u3051\u53d6\u308a\u3084\u3059\u3044\u306e\u3067\u3059\u304c\u3001RFC 2308\u306f\u305d\u306e\u610f\u5473\u3092\u5ec3\u3057\u3001\u5426\u5b9a\u5fdc\u7b54\u306eTTL\u306b\u7528\u3044\u308b\u3068\u5b9a\u7fa9\u3057\u3066\u3044\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<p>\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u8fd4\u3059\u969b\u306b\u306f\u3001\u4fdd\u5b58\u3057\u3066\u3044\u305f\u6642\u9593\u3092\u5f15\u3044\u305fTTL\u3092\u6dfb\u3048\u307e\u3059\u3002\u554f\u3044\u5408\u308f\u305b\u304c\u6765\u308b\u305f\u3073\u306b\u3001\u6700\u521d\u306e300\u79d2\u3078\u623b\u3059\u4ed5\u7d44\u307f\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u5225\u306e\u30ea\u30be\u30eb\u30d0\u30fc\u3078\u5f15\u304d\u7d99\u304c\u308c\u308b\u5834\u5408\u3082\u3001\u3053\u306e\u6b8b\u308a\u6642\u9593\u304c\u671f\u9650\u3092\u4f1d\u3048\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<h2>\u65b0\u3057\u3044A\u306eTTL\u3092\u77ed\u304f\u3057\u3066\u3082\u3001\u53e4\u3044\u4e0d\u5728\u60c5\u5831\u306f\u6b8b\u308b<\/h2>\n<p>\u6b21\u306f\u4ed5\u7d44\u307f\u3092\u78ba\u304b\u3081\u308b\u305f\u3081\u306e\u4eee\u5b9a\u4f8b\u3067\u3059\u3002\u3042\u308b\u30ea\u30be\u30eb\u30d0\u30fc\u304c09:00\u306b\u3001\u307e\u3060\u5b58\u5728\u3057\u306a\u3044\u540d\u524d\u306b\u3064\u3044\u3066TTL300\u79d2\u306eNXDOMAIN\u3092\u53d7\u3051\u53d6\u3063\u305f\u3068\u3057\u307e\u3059\u3002\u9014\u4e2d\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u524a\u9664\u3084\u7f6e\u63db\u3001\u5b9f\u88c5\u306b\u3088\u308bTTL\u306e\u77ed\u7e2e\u306f\u306a\u304f\u3001\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u306e\u5185\u5bb9\u306f\u66f4\u65b0\u5f8c\u306b\u4e00\u81f4\u3057\u3066\u3044\u3066\u3001\u6b63\u5e38\u306b\u554f\u3044\u5408\u308f\u305b\u3089\u308c\u308b\u6761\u4ef6\u3067\u3059\u3002\u969c\u5bb3\u6642\u306e\u671f\u9650\u5207\u308c\u60c5\u5831\u306e\u5229\u7528\u3082\u542b\u3081\u307e\u305b\u3093\u3002<\/p>\n<div style=\"width:720px;max-width:100%;margin:1.5em auto;overflow-x:auto;\">\n<table style=\"width:100%;min-width:620px;border-collapse:collapse;\">\n<caption>300\u79d2\u306e\u5426\u5b9a\u5fdc\u7b54\u3092\u4fdd\u5b58\u3057\u305f\u5f8c\u306b\u3001A\u3092\u8ffd\u52a0\u3057\u305f\u5834\u5408\u306e\u8a08\u7b97\u4f8b<\/caption>\n<thead>\n<tr>\n<th scope=\"col\">\u6642\u523b<\/th>\n<th scope=\"col\">\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u5074<\/th>\n<th scope=\"col\">\u3053\u306e\u30ea\u30be\u30eb\u30d0\u30fc\u5074<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>09:00<\/td>\n<td>\u540d\u524d\u306f\u307e\u3060\u306a\u3044<\/td>\n<td>NXDOMAIN\u3092\u4fdd\u5b58\u3002\u6b8b\u308a300\u79d2<\/td>\n<\/tr>\n<tr>\n<td>09:01<\/td>\n<td>\u540d\u524d\u3068A\u3092\u8ffd\u52a0\u3002\u65b0\u3057\u3044A\u306eTTL\u306f60\u79d2<\/td>\n<td>\u4fdd\u5b58\u6e08\u307f\u306e\u4e0d\u5728\u60c5\u5831\u306f\u6b8b\u308a240\u79d2<\/td>\n<\/tr>\n<tr>\n<td>09:03<\/td>\n<td>A\u304c\u5b58\u5728\u3059\u308b<\/td>\n<td>\u540c\u3058\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u4f7f\u3046\u554f\u3044\u5408\u308f\u305b\u306b\u306f\u3001\u6b8b\u308a120\u79d2\u306eNXDOMAIN\u3092\u8fd4\u3057\u5f97\u308b<\/td>\n<\/tr>\n<tr>\n<td>09:05<\/td>\n<td>A\u304c\u5b58\u5728\u3059\u308b<\/td>\n<td>\u901a\u5e38\u306e\u5426\u5b9a\u5fdc\u7b54\u30ad\u30e3\u30c3\u30b7\u30e5\u306f\u671f\u9650\u5207\u308c\u3002\u6b21\u306e\u554f\u3044\u5408\u308f\u305b\u3067\u306f\u6539\u3081\u3066\u89e3\u6c7a\u3059\u308b<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>09:01\u306bA\u3078\u8a2d\u5b9a\u3057\u305f60\u79d2\u306f\u3001<em>\u305d\u306eA\u3092\u53d6\u5f97\u3057\u305f\u5f8c<\/em>\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u95a2\u308f\u308b\u5024\u3067\u3059\u3002\u305d\u308c\u307e\u3067\u306b\u4fdd\u5b58\u3055\u308c\u305fNXDOMAIN\u306e\u6b8b\u308a240\u79d2\u3092\u300160\u79d2\u3078\u66f8\u304d\u63db\u3048\u308b\u3082\u306e\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u3053\u306e\u4f8b\u3067\u306f\u3001\u901a\u5e38\u306e\u5426\u5b9a\u5fdc\u7b54\u3092\u4f7f\u3048\u308b\u671f\u9650\u304c09:05\u306b\u6765\u308b\u306e\u3067\u3042\u3063\u3066\u300109:05\u306b\u4e16\u754c\u4e2d\u306e\u7aef\u672b\u3078\u65b0\u3057\u3044\u60c5\u5831\u304c\u4e00\u6589\u914d\u4fe1\u3055\u308c\u308b\u308f\u3051\u3067\u3082\u3042\u308a\u307e\u305b\u3093\u3002\u8868\u306f\u4ed5\u69d8\u304b\u3089\u8a08\u7b97\u3057\u305f\u8aac\u660e\u3067\u3001\u5b9f\u969b\u306eDNS\u74b0\u5883\u3092\u6e2c\u5b9a\u3057\u305f\u3082\u306e\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<sup class=\"source-note\"><a href=\"#ref1\">[1]<\/a><a href=\"#ref2\">[2]<\/a><\/sup><\/p>\n<h2>\u540c\u3058\u540d\u524d\u3060\u3051\u306b\u9589\u3058\u306a\u3044NXDOMAIN\u306e\u7bc4\u56f2<\/h2>\n<p>NXDOMAIN\u306b\u306f\u3001\u3055\u3089\u306b\u540d\u524d\u306e\u968e\u5c64\u3068\u306e\u95a2\u4fc2\u304c\u3042\u308a\u307e\u3059\u3002RFC 8020\u306f\u3001\u3042\u308b\u540d\u524d\u304c\u5b58\u5728\u3057\u306a\u3051\u308c\u3070\u3001\u305d\u306e\u4e0b\u306e\u540d\u524d\u3082\u5b58\u5728\u3057\u306a\u3044\u3068\u3057\u3066\u6271\u3046\u300cNXDOMAIN cut\u300d\u3092\u5b9a\u3081\u3066\u3044\u307e\u3059\u3002\u305f\u3068\u3048\u3070<code style=\"overflow-wrap:anywhere;\">foo.example<\/code>\u306e\u4e0d\u5b58\u5728\u3092\u4fdd\u5b58\u3057\u305f\u30ea\u30be\u30eb\u30d0\u30fc\u306f\u3001\u305d\u306e\u6709\u52b9\u671f\u9593\u4e2d\u3001\u914d\u4e0b\u306e<code style=\"overflow-wrap:anywhere;\">bar.foo.example<\/code>\u306b\u3082\u3001\u305d\u306e\u60c5\u5831\u306b\u57fa\u3065\u3044\u3066NXDOMAIN\u3092\u8fd4\u305b\u307e\u3059\u3002\u9006\u306b\u3001\u4e00\u3064\u306e\u914d\u4e0b\u540d\u304c\u306a\u3044\u3060\u3051\u3067\u3001\u96a3\u306e\u540d\u524d\u3084\u89aa\u307e\u3067\u306a\u3044\u3068\u306f\u5224\u65ad\u3067\u304d\u307e\u305b\u3093\u3002<sup class=\"source-note\"><a href=\"#ref3\">[3]<\/a><\/sup><\/p>\n<p>\u305f\u3060\u3057\u540cRFC\u306b\u306f\u3001\u3059\u3067\u306b\u4fdd\u5b58\u3057\u3066\u3044\u308b\u914d\u4e0b\u306e\u30c7\u30fc\u30bf\u3092\u305d\u306eTTL\u304c\u5207\u308c\u308b\u307e\u3067\u8fd4\u3057\u3066\u3088\u3044\u3053\u3068\u3084\u3001DNSSEC\u3067\u691c\u8a3c\u3055\u308c\u305fNXDOMAIN\u3060\u3051\u306b\u3053\u306e\u52d5\u4f5c\u3092\u9069\u7528\u3057\u3066\u3088\u3044\u3053\u3068\u3082\u66f8\u304b\u308c\u3066\u3044\u307e\u3059\u3002\u5225\u540d\u306e\u9023\u9396\u304c\u3042\u308b\u5834\u5408\u306f\u3001\u3069\u306e\u540d\u524d\u306e\u5b58\u5728\u304c\u5426\u5b9a\u3055\u308c\u305f\u306e\u304b\u3082\u78ba\u8a8d\u304c\u5fc5\u8981\u3067\u3059\u3002\u6700\u521d\u306b\u554f\u3044\u5408\u308f\u305b\u305f\u540d\u524d\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002<sup class=\"source-note\"><a href=\"#ref3\">[3]<\/a><\/sup><\/p>\n<h2>\u5f85\u3061\u6642\u9593\u3092\u5224\u65ad\u3059\u308b\u524d\u306b\u3001\u5fdc\u7b54\u306e\u7a2e\u985e\u3068\u76f8\u624b\u3092\u78ba\u304b\u3081\u308b<\/h2>\n<p>\u5909\u66f4\u5f8c\u306b\u898b\u3064\u304b\u3089\u306a\u3044\u3068\u304d\u306f\u3001\u307e\u305a\u540d\u524d\u3068\u30ec\u30b3\u30fc\u30c9\u306e\u7a2e\u985e\u3092\u305d\u308d\u3048\u3066\u3001\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u306e\u5fdc\u7b54\u3068\u3001\u5b9f\u969b\u306b\u5229\u7528\u3057\u3066\u3044\u308b\u30ea\u30be\u30eb\u30d0\u30fc\u306e\u5fdc\u7b54\u3092\u5206\u3051\u3066\u78ba\u8a8d\u3057\u307e\u3059\u3002\u5f8c\u8005\u304cNXDOMAIN\u307e\u305f\u306fNODATA\u306a\u3089\u3001Authority\u6b04\u306eSOA\u3068\u305d\u306eTTL\u306f\u3001\u5426\u5b9a\u5fdc\u7b54\u304c\u3042\u3068\u3069\u308c\u3060\u3051\u6b8b\u308a\u5f97\u308b\u304b\u3092\u5224\u65ad\u3059\u308b\u624b\u639b\u304b\u308a\u3067\u3059\u3002\u554f\u3044\u5408\u308f\u305b\u5148\u3054\u3068\u306b\u4fdd\u5b58\u3057\u305f\u6642\u70b9\u3084\u5185\u5bb9\u304c\u9055\u3048\u3070\u3001\u898b\u3048\u308b\u7d50\u679c\u3082\u9055\u3044\u5f97\u307e\u3059\u3002\u3053\u308c\u306f\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4ed5\u7d44\u307f\u304b\u3089\u5f97\u3089\u308c\u308b\u70b9\u691c\u306e\u9806\u5e8f\u3067\u3059\u3002<\/p>\n<p>SERVFAIL\u3084\u30bf\u30a4\u30e0\u30a2\u30a6\u30c8\u306a\u3089\u3001\u300c\u5b58\u5728\u3057\u306a\u3044\u300d\u3068\u3044\u3046\u5fdc\u7b54\u304c\u8fd4\u3063\u305f\u5834\u5408\u3068\u540c\u3058\u6271\u3044\u306b\u306f\u3067\u304d\u307e\u305b\u3093\u3002RFC 9520\u306f\u3001\u3053\u3046\u3057\u305f\u540d\u524d\u89e3\u6c7a\u306e\u5931\u6557\u306b\u3082\u3001\u7e70\u308a\u8fd4\u3057\u306e\u554f\u3044\u5408\u308f\u305b\u3092\u6291\u3048\u308b\u305f\u3081\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u8981\u6c42\u3057\u3066\u3044\u307e\u3059\u3002NXDOMAIN\u3068NODATA\u306f\u3001\u6709\u7528\u306a\u4e0d\u5b58\u5728\u306e\u60c5\u5831\u304c\u5f97\u3089\u308c\u305f\u5fdc\u7b54\u3068\u3057\u3066\u3001\u3053\u308c\u3089\u306e\u89e3\u6c7a\u5931\u6557\u3068\u306f\u533a\u5225\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u5358\u306b\u300cDNS\u3067\u5931\u6557\u3057\u305f\u300d\u3068\u307e\u3068\u3081\u305a\u3001\u4f55\u304c\u8fd4\u3063\u305f\u306e\u304b\u3092\u6b8b\u3059\u3053\u3068\u304c\u5207\u308a\u5206\u3051\u306b\u3064\u306a\u304c\u308a\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref4\">[4]<\/a><\/sup><\/p>\n<p>\u307e\u305f\u3001\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u3078\u63a5\u7d9a\u3067\u304d\u306a\u3044\u306a\u3069\u3001\u671f\u9650\u5207\u308c\u306e\u60c5\u5831\u3092\u66f4\u65b0\u3067\u304d\u306a\u3044\u5834\u9762\u3067\u306f\u3001\u53e4\u3044\u60c5\u5831\u3092\u8fd4\u3057\u3066\u53ef\u7528\u6027\u3092\u4fdd\u3064serve-stale\u3068\u3044\u3046\u4ed5\u7d44\u307f\u3082\u3042\u308a\u307e\u3059\u3002RFC 8767\u306f\u671f\u9650\u5207\u308c\u306e\u5426\u5b9a\u60c5\u5831\u306b\u3082\u8a00\u53ca\u3057\u3066\u3044\u307e\u3059\u3002\u305d\u306e\u305f\u3081\u3001\u5148\u307b\u3069\u306eTTL\u8a08\u7b97\u3092\u3001\u969c\u5bb3\u6642\u3082\u542b\u3081\u305f\u5fa9\u65e7\u6642\u523b\u306e\u4fdd\u8a3c\u306b\u306f\u3067\u304d\u307e\u305b\u3093\u3002\u6b63\u5e38\u6642\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u671f\u9650\u3001\u969c\u5bb3\u306b\u3088\u308b\u89e3\u6c7a\u5931\u6557\u3001\u671f\u9650\u5207\u308c\u60c5\u5831\u306e\u5229\u7528\u3092\u5206\u3051\u308b\u3053\u3068\u3067\u3001\u300c\u4f55\u3092\u5f85\u3063\u3066\u3044\u308b\u306e\u304b\u300d\u304c\u5177\u4f53\u7684\u306b\u306a\u308a\u307e\u3059\u3002<sup class=\"source-note\"><a href=\"#ref5\">[5]<\/a><\/sup><\/p>\n<h2>\u53c2\u8003\u8cc7\u6599<\/h2>\n<ol style=\"overflow-wrap:anywhere;\">\n<li id=\"ref1\">RFC Editor, <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc9499.html\">RFC 9499: DNS Terminology<\/a>\u30012024\u5e743\u6708\u3002\u30ea\u30be\u30eb\u30d0\u30fc\u3001\u6a29\u5a01\u30b5\u30fc\u30d0\u30fc\u3001TTL\u3001NXDOMAIN\u3001NODATA\u3001negative caching\u306e\u7528\u8a9e\u3092\u53c2\u7167\u3002<\/li>\n<li id=\"ref2\">RFC Editor, <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc2308.html\">RFC 2308: Negative Caching of DNS Queries (DNS NCACHE)<\/a>\u30011998\u5e743\u6708\u3002\u00a7\u00a71\u301c6\u3002\u4e0d\u5b58\u5728\u5fdc\u7b54\u306e\u8b58\u5225\u3001SOA\u304b\u3089\u6c7a\u307e\u308bTTL\u3001\u4fdd\u5b58\u6642\u3068\u8fd4\u7b54\u6642\u306e\u6271\u3044\u3092\u53c2\u7167\u3002\u89e3\u6c7a\u5931\u6557\u306b\u95a2\u3059\u308b\u65e7\u00a77\u306f\u4e0b\u8a18RFC 9520\u306e\u66f4\u65b0\u3068\u533a\u5225\u3002<\/li>\n<li id=\"ref3\">RFC Editor, <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc8020.html\">RFC 8020: NXDOMAIN: There Really Is Nothing Underneath<\/a>\u30012016\u5e7411\u6708\u3002\u00a7\u00a71.1\u301c3.2\u3002NXDOMAIN cut\u3001\u65e2\u5b58\u30ad\u30e3\u30c3\u30b7\u30e5\u30fbDNSSEC\u306e\u6761\u4ef6\u3001\u5225\u540d\u9023\u9396\u306e\u6271\u3044\u3092\u53c2\u7167\u3002<\/li>\n<li id=\"ref4\">RFC Editor, <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc9520.html\">RFC 9520: Negative Caching of DNS Resolution Failures<\/a>\u30012023\u5e7412\u6708\u3002\u00a7\u00a72\u301c3\u3002NXDOMAIN\/NODATA\u3068\u89e3\u6c7a\u5931\u6557\u306e\u533a\u5225\u3001\u5931\u6557\u3092\u4fdd\u5b58\u3059\u308b\u8981\u4ef6\u3092\u53c2\u7167\u3002<\/li>\n<li id=\"ref5\">RFC Editor, <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc8767.html\">RFC 8767: Serving Stale Data to Improve DNS Resiliency<\/a>\u30012020\u5e743\u6708\u3002\u00a7\u00a74\u301c7\u30fb10\u3002\u66f4\u65b0\u3067\u304d\u306a\u3044\u671f\u9650\u5207\u308c\u60c5\u5831\u306e\u5229\u7528\u6761\u4ef6\u3068\u5426\u5b9a\u60c5\u5831\u3078\u306e\u5f71\u97ff\u3092\u53c2\u7167\u3002<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\u65b0\u3057\u3044\u30db\u30b9\u30c8\u540d\u3068IP\u30a2\u30c9\u30ec\u30b9\u3092DNS\u306b\u767b\u9332\u3057\u305f\u306e\u306b\u3001\u624b\u5143\u3067\u306f\u307e\u3060\u300c\u898b\u3064\u304b\u3089\u306a\u3044\u300d\u3068\u8fd4\u3063\u3066\u304f\u308b\u3002\u767b\u9332\u306b\u5931\u6557\u3057\u305f\u3068\u306f\u9650\u308a\u307e\u305b\u3093\u3002DNS\u306f\u898b\u3064\u304b\u3063\u305f\u30c7\u30fc\u30bf\u3060\u3051\u3067\u306a\u304f\u3001\u5b58\u5728\u3057\u306a\u3044\u3068\u3044\u3046\u5fdc\u7b54\u3082\u671f\u9650\u4ed8\u304d\u3067\u4fdd\u5b58\u3059\u308b\u304b\u3089\u3067\u3059\u3002\u3053\u306e\u4ed5\u7d44\u307f [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":936,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":false,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[29],"tags":[257,258],"class_list":["post-939","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-communications-networking","tag-dns","tag-negative-caching"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/quantumsea.net\/wp-content\/uploads\/2026\/10\/qs-dns-negative-cache-20261014-featured-11edb435bfd2.png","_links":{"self":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/939","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=939"}],"version-history":[{"count":1,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/939\/revisions"}],"predecessor-version":[{"id":941,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/posts\/939\/revisions\/941"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=\/wp\/v2\/media\/936"}],"wp:attachment":[{"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=939"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=939"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/quantumsea.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=939"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}