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          <div class="eyebrow page-kicker">Reference Catalog</div>
          <h1>Browse the CIDR notation reference directly in the website.</h1>
          <p class="page-intro">This page embeds the current monthly CIDR publication directly in HTML so the catalog opens immediately without exposing a separate raw JSON action.</p>
          <p class="page-intro seo-links">Return to the <a href="downloads.html">IP geolocation downloads hub</a>, browse the <a href="reference-ports.html">ports reference</a> and <a href="reference-root-zone.html">root zone database</a>, or review the <a href="methodology.html">monthly reference publication methodology</a>.</p>
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          <h3>Prefix notation context</h3>
          <p class="card-text">This catalog helps users translate CIDR prefix notation into host counts and netmasks, which is useful when reading IP allocation and prefix-footprint material.</p>
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          <h3>Operational interpretation</h3>
          <p class="card-text">CIDR reference data supports engineers, analysts, and data users who need a quick lookup while reviewing IP-oriented datasets, reports, or troubleshooting tasks.</p>
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          <h3>Related IP geolocation paths</h3>
          <p class="card-text">Use the <a href="ip-geolocation-data.html">IP geolocation guide</a> for broader context, or the <a href="downloads.html">downloads hub</a> for the monthly file indexes.</p>
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      <h2>How to use the CIDR reference</h2>
      <p>
        This page is a compact CIDR reference for prefix width, host-count scale, and dotted-decimal netmask interpretation. It is designed for quick lookup, but it also supports explanatory use when a visitor needs a plain-language bridge between network notation and operational meaning.
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        Review the rows to compare prefixes, host counts, and masks side by side. The surrounding summary explains the page as a practical IPv4 reference rather than leaving the table without context.
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