# /6 Subnet Mask (252.0.0.0) – Hosts, Range & FAQ

> The /6 subnet mask is 252.0.0.0. A /6 block holds 67,108,864 addresses with 67,108,862 usable hosts — ranges, wildcard, binary math and FAQs.

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# /6 Subnet Mask ReferenceIPv4

Four /8 networks bundled under mask 252.0.0.0: that is a /6, holding 67,108,864 addresses. It dwarfs any conceivable deployment, so the prefix survives mainly in textbooks and route-aggregation worksheets.

The /6 subnet mask is 252.0.0.0, equivalent to 3.255.255.255 as a wildcard. A /6 block contains 67,108,864 IP addresses (67,108,862 usable hosts).

## /6 facts at a glance

- **Subnet mask:** 252.0.0.0
- **Wildcard mask:** 3.255.255.255
- **Binary mask:** 11111100.00000000.00000000.00000000
- **Total addresses:** 67,108,864
- **Usable hosts:** 67,108,862 (excludes network & broadcast)
- **Block size:** 67,108,864 addresses (226)
- **Typical role:** Aggregation and supernetting

## Example /6 networks

A /6 spans a large share of the address space, so one aligned example says it all.

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 196.0.0.0/6 | 196.0.0.1 – 199.255.255.254 | 67,108,862 |

## How to calculate a /6 mask

A /6 mask sets the first 6 bits of a 32-bit number to 1 and leaves the remaining 26 bits as 0. In binary that reads `11111100.00000000.00000000.00000000`, which converts to dotted decimal `252.0.0.0`. Each block covers a contiguous run of 226 = 67,108,864 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `3.255.255.255`.

## Where /6 is used

- Aggregation drills: combining neighboring /8s into one summary line.
- Visualizing the address map, for example 64.0.0.0/6 covering 64.0.0.0 through 67.255.255.255.
- Bit-boundary exercises where the mask stops mid-first-octet.

Alignment rule: a /6 network must start on a first octet divisible by four, such as 64, 68, 124, or 220.

## Frequently asked questions

**What is the subnet mask for /6?**

252.0.0.0, with wildcard 3.255.255.255. Six leading one-bits leave 26 host bits.

**How many addresses are in a /6?**

67,108,864 total; 67,108,862 usable after the standard two-address deduction.

**Why would a block this large never be deployed?**

Even the largest carriers control only a handful of /8s, and no routing domain approaches tens of millions of hosts. The prefix exists for aggregation math.

## Open this block in a calculator

[Open the /6 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=196.0.0.0%2F6)

[Get the /6 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F6)

### Related prefixes

[/5](https://itinsighthub.com/subnet/5/)[/7](https://itinsighthub.com/subnet/7/)[/24](https://itinsighthub.com/subnet/24/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /5 subnet mask
/7 subnet mask →

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