เครื่องคำนวณ CIDR

วิธีใช้เครื่องมือนี้

1. 1

   Type the number of hosts you need to address into the 'Hosts needed' field.

2. 2

   Read the 'Smallest CIDR fitting' row to get the prefix length (for example /26).

3. 3

   Check the 'Total addresses' and 'Usable hosts' rows to confirm the block is big enough.

4. 4

   Look at the 'Address space wasted' row to see how many addresses you would leave unused at that prefix.

เครื่องคำนวณ CIDR คืออะไร?

กรณีการใช้งานทั่วไป

• Sizing a new office VLAN by entering the expected device count and picking the prefix that leaves a little headroom.

• Quickly checking whether a /24 is overkill for a subnet that only needs 30 hosts.

• Comparing the wasted-address count across host estimates before you carve up a parent block.

• Teaching subnetting students why 50 hosts needs 64 addresses and not 50.

• Planning IP allocation for a fleet of IoT devices and confirming the block will not run out as you scale.

• Sanity-checking a colleague's subnet proposal by reproducing the host-to-prefix math in seconds.

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