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IPv6 /112 prefix

A /112 leaves 16 bits for subnets and hosts: 65,536 addresses.

IPv6 /112 at a glance

Mask
ffff:ffff:ffff:ffff:ffff:ffff:ffff:0
Mask (expanded)
ffff:ffff:ffff:ffff:ffff:ffff:ffff:0000
Host bits
16
Addresses
65,536
Nibble-aligned
Yes, the boundary falls on a hex digit
Reverse DNS zone
0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa

Typical uses of a /112

A /112 leaves the last 16 bits (one hextet) for hosts: 65,536 addresses, easy to read because the boundary falls on a colon. It is used for small static pools such as container or service VIP ranges, and by some operators for links before /127 was standardised.

Example: 2001:db8::/112

First address
2001:db8::
Last address
2001:db8::ffff
Last (expanded)
2001:0db8:0000:0000:0000:0000:0000:ffff
Next /112
2001:db8::1:0/112

Uses the documentation prefix 2001:db8::/32 (RFC 3849). IPv6 has no broadcast address, so every address in the range is assignable, except where a platform reserves some.

Find the /112 for an address

What a /112 contains

Smaller prefixHow many
/12732,768
/12865,536

How many /112s fit

In aNumber of /112s
/321,208,925,819,614,629,174,706,176
/4818,446,744,073,709,551,616
/5672,057,594,037,927,936
/64281,474,976,710,656

Cloud support for /112

PlatformIPv6 subnet size/112?
AWS VPC/44 to /64 in steps of /4No
Azure VNetexactly /64No
Google Cloud VPC/64 (from the VPC's /48)No