What a /29 subnet is: eight addresses
A /29 holds 8 addresses, 6 usable, with a block size of 8 in the last octet. It is the usual size of a small static allocation from an internet provider.
At a glance
- Subnet mask
- 255.255.255.248
- Wildcard mask
- 0.0.0.7
- Total addresses
- 8
- Usable hosts
- 6
- Block size in the last octet
- 8
- Host bits
- 3 of 32
In detail
The mask is 255.255.255.248. After the network address, the broadcast address and the provider's gateway, you typically get five usable addresses out of the eight.
Enough for a firewall, a mail server, a web server and a spare. It is the smallest allocation that supports more than one public service without port translation.
Plan which service takes which address before you configure anything. Renumbering a public address means updating DNS, reverse DNS and every allowlist that mentions it.
Examples
198.51.100.8/29
network 198.51.100.8
gateway 198.51.100.9 (provider)
usable 198.51.100.10 to 198.51.100.14 (5 left for you)
broadcast 198.51.100.15Things that catch people out
- Valid last octets are multiples of 8. 198.51.100.10/29 is not a network address, the block is 198.51.100.8/29.
- Providers count a /29 as eight addresses in their sales copy and five in practice. Confirm which number is on the order.
Try it: IP Subnet Calculator
Enter any IPv4 address with a prefix or a dotted mask and get the network address, broadcast address, wildcard mask, usable host range, address class, and the hex and binary forms.
IP Subnet Calculator
LOCAL · Browser-OnlyCalculate IP subnet details, network ranges, and CIDR notation
192.168.1.0192.168.1.255255.255.255.00.0.0.255192.168.1.0/24192.168.1.1 - 192.168.1.254192.168.1.1192.168.1.254256254C0xC0A8016411000000.10101000.00000001.01100100Split into two /25 subnets
Dividing 192.168.1.0/24 one prefix deeper.
Common Subnet Masks
Related IPv4 subnets
All ipv4 subnets →What a /30 subnet is: a point-to-point link
A /30 uses the mask 255.255.255.252 and gives 2 usable addresses. What it is for and where it goes wrong.
What a /28 subnet is: sixteen addresses
A /28 uses the mask 255.255.255.240 and gives 14 usable addresses. What it is for and where it goes wrong.
What a /31 subnet is: a point-to-point link with no waste
A /31 uses the mask 255.255.255.254 and gives 2 usable addresses. What it is for and where it goes wrong.
What a /32 subnet is: a single host
A /32 uses the mask 255.255.255.255 and gives 1 usable addresses. What it is for and where it goes wrong.
What a /0 subnet is: the default route
A /0 uses the mask 0.0.0.0 and gives 4,294,967,294 usable addresses. What it is for and where it goes wrong.
What a /4 subnet is: the multicast block
A /4 uses the mask 240.0.0.0 and gives 268,435,454 usable addresses. What it is for and where it goes wrong.
Tools for this
- IP Subnet Calculator Free online IP subnet calculator - calculate IP subnet details, CIDR notation, and network address ranges
- IP Address Lookup Free online IP address lookup - find your public IP address and basic network information
- Number Base Converter Free online number base converter - convert numbers between decimal, binary, octal, and hexadecimal