What is a /15 subnet?
131,070 usable hosts out of 131,072 addresses, behind netmask 255.254.0.0.
| Prefix | /15 |
|---|---|
| Netmask | 255.254.0.0 |
| Wildcard | 0.1.255.255 |
| Total addresses | 131,072 |
| Usable hosts | 131,070 |
| Example block | 10.0.0.0/15 |
| Usable host range | 10.0.0.1 – 10.1.255.254 |
| Broadcast | 10.1.255.255 |
A /15 fixes the first 15 bits of the address as the network and leaves 17 for hosts — 131,072 addresses in all.
Of those, 131,070 can be given to a machine: the first address names the network itself, and the last is the broadcast address.
A block this large is an allocation rather than a subnet — a whole private range to carve up, or something a regional registry hands out. You would not put hosts directly in it.
It is 512 times the size of a /24.
Other subnet sizes
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