What is a /16 subnet?
65,534 usable hosts out of 65,536 addresses, behind netmask 255.255.0.0.
| Prefix | /16 |
|---|---|
| Netmask | 255.255.0.0 |
| Wildcard | 0.0.255.255 |
| Total addresses | 65,536 |
| Usable hosts | 65,534 |
| Example block | 10.0.0.0/16 |
| Usable host range | 10.0.0.1 – 10.0.255.254 |
| Broadcast | 10.0.255.255 |
A /16 fixes the first 16 bits of the address as the network and leaves 16 for hosts — 65,536 addresses in all.
Of those, 65,534 can be given to a machine: the first address names the network itself, and the last is the broadcast address.
This is the usual size for a VPC or a site: room for tens of thousands of addresses, divided into smaller subnets per zone or per service.
It is 256 times the size of a /24.
Other subnet sizes
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