0.0.0.0 Subnet Mask
0.0.0.0 is the subnet mask for a /0 network — 4,294,967,294 usable hosts out of 4,294,967,296 addresses.
CIDR Prefix
/0
Wildcard Mask
255.255.255.255
Total Addresses
4,294,967,296
Usable Hosts
4,294,967,294
Network Bits
0
Host Bits
32
0.0.0.0 in Binary
Each octet is eight bits. The highlighted bits are the 0 network bits; the rest are the 32 host bits that vary within the subnet.
0
0
0
0
Networks Using 0.0.0.0
Neighbouring Masks
Frequently Asked Questions
What CIDR prefix is 0.0.0.0?
0.0.0.0 is /0 in CIDR notation. The mask sets the first 0 of the 32 bits in an IPv4 address to 1, marking them as the network portion, and leaves the remaining 32 bits as 0 for hosts.
How many hosts does 0.0.0.0 allow?
A network with mask 0.0.0.0 holds 4,294,967,296 addresses, of which 4,294,967,294 are usable by hosts — the network address and the broadcast address are reserved.
What is the wildcard mask for 0.0.0.0?
The wildcard mask for 0.0.0.0 is 255.255.255.255. It is the bitwise inverse: every 1 in the subnet mask becomes a 0 and every 0 becomes a 1. Cisco access lists and OSPF network statements take the wildcard form rather than the subnet mask.
Standards
- RFC 950 — Internet Standard Subnetting Procedure
Defines the dotted-decimal subnet mask itself, and the rule that the network and broadcast addresses are not assignable to hosts.
- RFC 4632 — Classless Inter-Domain Routing (CIDR)
Establishes the /0 prefix notation that 0.0.0.0 is equivalent to, and requires masks to be contiguous — which is why exactly 33 of the 4.3 billion possible values are valid.