# /2 Subnet Mask (192.0.0.0) – Hosts, Range & FAQ

> The /2 subnet mask is 192.0.0.0. A /2 block holds 1,073,741,824 addresses with 1,073,741,822 usable hosts — ranges, wildcard, binary math and FAQs.

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# /2 Subnet Mask ReferenceIPv4

Fix the top two bits and one quarter of IPv4, some 1,073,741,824 addresses, collapses into a single /2 behind mask 192.0.0.0. Its best party trick is historical: the old Class C, D, and E ranges together fill exactly one /2.

The /2 subnet mask is 192.0.0.0, equivalent to 63.255.255.255 as a wildcard. A /2 block contains 1,073,741,824 IP addresses (1,073,741,822 usable hosts).

## /2 facts at a glance

- **Subnet mask:** 192.0.0.0
- **Wildcard mask:** 63.255.255.255
- **Binary mask:** 11000000.00000000.00000000.00000000
- **Total addresses:** 1,073,741,824
- **Usable hosts:** 1,073,741,822 (excludes network & broadcast)
- **Block size:** 1,073,741,824 addresses (230)
- **Typical role:** Aggregation and supernetting

## Example /2 networks

A /2 spans a large share of the address space, so one aligned example says it all.

| Network | Usable range | Usable hosts |
| --- | --- | --- |
| 192.0.0.0/2 | 192.0.0.1 – 255.255.255.254 | 1,073,741,822 |

## How to calculate a /2 mask

A /2 mask sets the first 2 bits of a 32-bit number to 1 and leaves the remaining 30 bits as 0. In binary that reads `11000000.00000000.00000000.00000000`, which converts to dotted decimal `192.0.0.0`. Each block covers a contiguous run of 230 = 1,073,741,824 addresses, and every block starts at a multiple of that size. The wildcard simply flips every bit, giving `63.255.255.255`.

## Where /2 is used

- CIDR hierarchy lessons: four /2 blocks tile the whole address space.
- Aggregation arithmetic practice with very large blocks.
- Understanding how the legacy classful map sits inside modern CIDR.

The block 192.0.0.0/2 runs from 192.0.0.0 through 255.255.255.255, sweeping up former Class C (192-223), multicast Class D (224-239), and reserved Class E (240-255) in one stroke.

## Frequently asked questions

**What is the subnet mask for a /2?**

192.0.0.0; the wildcard is 63.255.255.255. Two leading one-bits leave 30 host bits.

**How many addresses does a /2 contain?**

1,073,741,824 total, with 1,073,741,822 usable under the usual network-and-broadcast convention.

**How many /8 networks fit in a /2?**

Four. A /2 groups eight first-octet values, and each /8 consumes two of them.

## Open this block in a calculator

[Open the /2 block in the subnet calculator](https://itinsighthub.com/subnet-calculator/?q=192.0.0.0%2F2)

[Get the /2 wildcard mask →](https://itinsighthub.com/wildcard-mask-calculator/?q=%2F2)

### Related prefixes

[/1](https://itinsighthub.com/subnet/1/)[/3](https://itinsighthub.com/subnet/3/)[/24](https://itinsighthub.com/subnet/24/)[/26](https://itinsighthub.com/subnet/26/)[/28](https://itinsighthub.com/subnet/28/)[/30](https://itinsighthub.com/subnet/30/)

← /1 subnet mask
/3 subnet mask →

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