{
  "id": "08",
  "content": [
    {
      "type": "heading",
      "text": "TTL, Caching and Propagation"
    },
    {
      "type": "text",
      "html": "<code>TTL</code> tells resolvers how long they may cache a DNS answer. Lower TTLs can make planned changes easier; higher TTLs can reduce repeated lookups for stable records."
    },
    {
      "type": "text",
      "html": "Propagation is not a magical single event. Different resolvers may keep old answers until their cache expires, which is why some users see changes before others."
    },
    {
      "type": "callout",
      "style": "info",
      "html": "<strong>Practice:</strong> Lower TTL before major migrations when possible, wait for old caches to age out, make the change, then raise TTL again after stability is confirmed."
    }
  ],
  "quiz": {
    "questions": [
      {
        "id": "q1",
        "type": "single",
        "text": "What does TTL control?",
        "options": [
          {
            "id": "a",
            "text": "How long DNS answers may be cached"
          },
          {
            "id": "b",
            "text": "How many words a title tag can have"
          },
          {
            "id": "c",
            "text": "How bright an image appears"
          }
        ],
        "correct": [
          "a"
        ]
      },
      {
        "id": "q2",
        "type": "single",
        "text": "Why can DNS changes appear at different times?",
        "options": [
          {
            "id": "a",
            "text": "Resolvers cache answers for different remaining times"
          },
          {
            "id": "b",
            "text": "Every browser invents random domains"
          },
          {
            "id": "c",
            "text": "IP addresses cannot change"
          }
        ],
        "correct": [
          "a"
        ]
      }
    ]
  }
}