/0 Subnet Mask Reference

The subnet mask for prefix length /0 is 0.0.0.0. Default route — covers the entire IPv4 address space.

Prefix Length/0
Subnet Mask0.0.0.0
Wildcard Mask255.255.255.255
Hex Value00000000
Usable Hosts4.294.967.294
Network Bits0 / 32

Binary Representation

Subnet Mask00000000.00000000.00000000.00000000
Wildcard Mask11111111.11111111.11111111.11111111

1-bits (network): 0 ·  0-bits (host): 32 ·  Total: 32 bits

Common Uses for 0.0.0.0

  • Default route — matches all IP addresses
  • Internet routing tables

Frequently Asked Questions

What is the subnet mask for /0?

The subnet mask for prefix length /0 is 0.0.0.0. In hexadecimal it is 0x00000000. The binary representation is 00000000.00000000.00000000.00000000.

What is the inverse (wildcard) mask of 0.0.0.0?

The wildcard mask (inverse mask) of 0.0.0.0 is 255.255.255.255. Wildcard masks are used in Cisco IOS ACLs and OSPF configurations to specify which bits of an IP address to match.

How many host IPs does 0.0.0.0 give?

With subnet mask 0.0.0.0 (/0), you get 4.294.967.296 total IPs, minus 2 reserved (network + broadcast) = 4.294.967.294 usable host addresses.

What CIDR prefix corresponds to 0.0.0.0?

The subnet mask 0.0.0.0 corresponds to CIDR prefix /0. This means 0 bits are used for the network portion and 32 bits for host addresses.

Complete Subnet Mask Reference /0–/32

PrefixSubnet MaskWildcardHexUsable Hosts
/00.0.0.0255.255.255.255000000004.294.967.294
/1128.0.0.0127.255.255.255800000002.147.483.646
/2192.0.0.063.255.255.255C00000001.073.741.822
/3224.0.0.031.255.255.255E0000000536.870.910
/4240.0.0.015.255.255.255F0000000268.435.454
/5248.0.0.07.255.255.255F8000000134.217.726
/6252.0.0.03.255.255.255FC00000067.108.862
/7254.0.0.01.255.255.255FE00000033.554.430
/8255.0.0.00.255.255.255FF00000016.777.214
/9255.128.0.00.127.255.255FF8000008.388.606
/10255.192.0.00.63.255.255FFC000004.194.302
/11255.224.0.00.31.255.255FFE000002.097.150
/12255.240.0.00.15.255.255FFF000001.048.574
/13255.248.0.00.7.255.255FFF80000524.286
/14255.252.0.00.3.255.255FFFC0000262.142
/15255.254.0.00.1.255.255FFFE0000131.070
/16255.255.0.00.0.255.255FFFF000065.534
/17255.255.128.00.0.127.255FFFF800032.766
/18255.255.192.00.0.63.255FFFFC00016.382
/19255.255.224.00.0.31.255FFFFE0008.190
/20255.255.240.00.0.15.255FFFFF0004.094
/21255.255.248.00.0.7.255FFFFF8002.046
/22255.255.252.00.0.3.255FFFFFC001.022
/23255.255.254.00.0.1.255FFFFFE00510
/24255.255.255.00.0.0.255FFFFFF00254
/25255.255.255.1280.0.0.127FFFFFF80126
/26255.255.255.1920.0.0.63FFFFFFC062
/27255.255.255.2240.0.0.31FFFFFFE030
/28255.255.255.2400.0.0.15FFFFFFF014
/29255.255.255.2480.0.0.7FFFFFFF86
/30255.255.255.2520.0.0.3FFFFFFFC2
/31255.255.255.2540.0.0.1FFFFFFFE2
/32255.255.255.2550.0.0.0FFFFFFFF1