/30 vs /32 — Subnet Comparison
A /30 subnet is 4× larger than a /32. Every additional bit in the prefix halves the address space — the 2-bit difference between these two means /30 has 22 = 4 times as many addresses.
2 usable hosts — point-to-point link
Typical Uses
- →WAN point-to-point link between routers
- →BGP peering session
- →Dedicated leased line addressing
Single host address
Typical Uses
- →Host route in routing table
- →Loopback interface address
- →Security group rule for a single IP
Key Differences
How 4 /32 Subnets Divide a /30
Example using 10.0.0.0/30 as the parent block.
| # | CIDR | Network | First Usable | Last Usable | Broadcast | Hosts |
|---|---|---|---|---|---|---|
| 1 | 10.0.0.0/32 | 10.0.0.0 | 10.0.0.0 | 10.0.0.0 | 10.0.0.0 | 1 |
| 2 | 10.0.0.1/32 | 10.0.0.1 | 10.0.0.1 | 10.0.0.1 | 10.0.0.1 | 1 |
| 3 | 10.0.0.2/32 | 10.0.0.2 | 10.0.0.2 | 10.0.0.2 | 10.0.0.2 | 1 |
| 4 | 10.0.0.3/32 | 10.0.0.3 | 10.0.0.3 | 10.0.0.3 | 10.0.0.3 | 1 |
FAQ
What is the difference between /30 and /32?
A /30 has 2 usable hosts
and a /32 has 1.
The subnet masks differ: /30 uses 255.255.255.252
while /32 uses 255.255.255.255.
Every additional bit in the prefix halves the number of addresses — so the 2-bit gap means
/30 is exactly 4× larger.
How many /32 subnets fit in a /30?
Exactly 4 /32 subnets fit perfectly inside one /30 with no wasted space. To split a /30 into /32s, just increment the last 2 bits of the network address for each new subnet.
Which should I choose?
/30 is typically used for: WAN point-to-point link. /32 is better for: Single host — firewall rules, host routes. Choose the smallest prefix that comfortably fits your host count — over-allocating wastes address space, but under-allocating means painful renumbering later.