{
  "id": 12989732,
  "title": "How to subnet for the CCNA without memorizing a chart",
  "url": "https://urgent.news/2026/10/09/how-to-subnet-for-the-ccna-without-memorizing-a-chart",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-10-09T00:18:05.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/crushcert/how-to-subnet-for-the-ccna-without-memorizing-a-chart-55co"
  },
  "original_language": "en",
  "account": "Subnetting is a crucial topic in the CCNA exam, appearing both as standalone questions and within routing and lab tasks. Many learners struggle by trying to memorize masks and host counts. Instead, focus on a method that needs only the powers of two to be memorized. An IPv4 address consists of 32 bits, written in four octets of 8 bits each. A prefix like /26 indicates that the first 26 bits represent the network, while the remaining 6 are for hosts. The key to subnetting is understanding that an IPv4 address is divided into an interesting octet and the rest, with the latter being subject to arithmetic operations. The three-step method for subnetting involves finding the interesting octet, determining the block size, and identifying the block your address falls into. For instance, the host 192.168.10.77/26 falls within the .64 subnet range, with a usable count of 62 addresses. Another example is the host 10.4.130.9/22, which falls within the .128 subnet range, having 1,022 usable addresses. The final example involves designing subnets with at least 30 hosts each from the 172.16.5.0/24 network, resulting in a /27 prefix and a third subnet of 172.16.5.64/27. Avoid common mistakes such as counting from the wrong end, forgetting to subtract 2 for the network and broadcast addresses, and mixing up borrowed and host bits. Practice regularly to make the process automatic, as subnetting is often a hidden challenge in other exam topics like routing configurations and connectivity issues.",
  "summary": "Subnetting is the one CCNA topic that shows up everywhere: in its own questions, hidden inside routing questions, and in the lab tasks where you have to type an address that actually fits the network. Most people try to memorize a chart of masks and host counts. The chart works until you're nervous, and then it doesn't. Here's the method I'd teach instead. It has three steps, it needs nothing…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}