/29 Subnet Mask: 255.255.255.248
A /29 IPv4 subnet uses mask 255.255.255.248. It contains 8 total addresses and, under traditional subnetting, 6 usable host addresses. The block size is 8 in the fourth octet and the wildcard mask is 0.0.0.7.
/29 quick reference
| Prefix | /29 |
|---|---|
| Subnet mask | 255.255.255.248 |
| Wildcard mask | 0.0.0.7 |
| Total addresses | 8 |
| Traditional usable hosts | 6 |
| Block size | 8 in the fourth octet |
Worked example: 192.168.10.0/29
| Role | Address |
|---|---|
| Network address | 192.168.10.0 |
| First usable host | 192.168.10.1 |
| Last usable host | 192.168.10.6 |
| Broadcast address | 192.168.10.7 |
| Next /29 network | 192.168.10.8/29 |
The final mask octet is 248, so 256 - 248 = 8. Starting at zero, valid /29 boundaries in a /24 are 0, 8, 16, 24 and so on. The address 192.168.10.7 is not a host in this example; all host bits are one, making it the directed broadcast address.
All four starting ranges
| Network | Usable range | Broadcast |
|---|---|---|
| 192.168.10.0/29 | .1–.6 | .7 |
| 192.168.10.8/29 | .9–.14 | .15 |
| 192.168.10.16/29 | .17–.22 | .23 |
| 192.168.10.24/29 | .25–.30 | .31 |
A /29 suits a small routed segment, management network or lab that needs no more than six traditional host addresses. Leave operational growth in the design; choosing /29 for exactly six devices gives no spare host address.
Cisco wildcard and verification
The inverse of 255.255.255.248 is 0.0.0.7. For an authorised Cisco ACL exercise, access-list 10 permit 192.168.10.0 0.0.0.7 matches this /29 range. Verify the intended policy before applying any ACL; an address calculation does not decide whether traffic should be permitted.
Use the formula 2^(32-29) = 8 total addresses, then subtract the traditional network and broadcast addresses to get 6 usable hosts. The special /31 point-to-point rule does not change /29 calculations.
Frequently asked questions
What is the subnet mask for /29?
The /29 subnet mask is 255.255.255.248.
How many usable hosts are in a /29?
A /29 has 8 total IPv4 addresses and 6 traditional usable host addresses after reserving the network and broadcast addresses.
What is the /29 wildcard mask?
The wildcard mask is 0.0.0.7, the inverse of 255.255.255.248.
What is the block size of a /29?
The block size is 8 in the fourth octet, so subnet boundaries occur at 0, 8, 16, 24 and continuing multiples of 8.
Primary sources
- RFC 1878: Variable Length Subnet Table for IPv4
- Cisco: understand host and subnet quantities
- Cisco IOS: wildcard masks in access lists
Port registrations describe assigned names, not a guarantee about the process actually listening on a device. Confirm the local process and configuration before changing a firewall.
Related guides
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