Cloud & Infrastructure
How to explain IP block sizes to lessees
A leasing info page succeeds when a buyer can turn a vague need into a block size quickly. This guide walks through the decisions that make such a page genuinely useful.
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Step one: translate blocks into host counts
Begin with a table that converts each common prefix length into the number of addresses it contains, then subtract the addresses typically unavailable for hosts. A /24 holds 256 addresses, a /23 holds 512, and a /22 holds 1,024. Label each row with plain wording so a non-specialist can follow. Include a short note that usable counts are slightly lower because of network and broadcast addresses. Keep the table near the top, because every later decision about price, routing and justification depends on the buyer understanding what each block actually contains.
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Step two: match size to workload
Next, connect sizes to real situations. A small hosting company launching a few dozen customer servers may need far less than a regional ISP assigning addresses to subscribers. Ask the reader to count current devices, expected growth over the lease term, and any services needing dedicated addresses such as mail or load balancers. Suggest adding a margin for growth without leasing excess. Worked example: a managed hosting team with 180 servers expects 40 percent growth, reaching about 252, which points toward a /24 rather than a smaller block that would force a second lease within months.
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Step three: check practical constraints before leasing
Finally, list checks the buyer should complete before committing. Confirm the registry region, the lease length, whether the block has a clean reputation history, and whether upstream providers will route a block of that size. Smaller prefixes are often filtered by networks, so routability can limit useful choices. Explain the paperwork a lessor commonly requests and who the contact is for abuse reports. Close the page with a request form asking for block size, region and term, so a reader who has worked through the steps can submit a precise inquiry rather than a general question.