IPv4 Class Table
Understanding IPv4 Address Classes (A, B, C, D, E)
Overview
Before CIDR (Classless Inter-Domain Routing), IPv4 used a class-based addressing system. Although classful addressing is no longer used for routing today, understanding address classes is still incredibly valuable for:
- Certifications (CCNA, Network+, Security+, etc.)
- Legacy networks
- Historical context
- Understanding how early Internet addressing worked
- Recognizing multicast and reserved ranges
What This CSV Contains
The IPv4 Class Table CSV gives you a clear breakdown of:
- Class A: 1.0.0.0 – 126.255.255.255
- Class B: 128.0.0.0 – 191.255.255.255
- Class C: 192.0.0.0 – 223.255.255.255
- Class D: 224.0.0.0 – 239.255.255.255 (Multicast)
- Class E: 240.0.0.0 – 255.255.255.254 (Reserved)
For each class, the CSV includes:
- First and last IP
- Default netmask
- Typical CIDR
- Number of classful networks
- Approximate hosts per network
- Expert-level historical notes
This CSV is ideal for educational content, subnetting primers, and explaining how modern CIDR evolved.
| Class | First Address | Last Address | Default Netmask | Typical CIDR | Number of Classful Networks | Hosts per Network (Approx) | Notes |
|---|---|---|---|---|---|---|---|
| A | 1.0.0.0 | 126.255.255.255 | 255.0.0.0 | /8 | 128 | 16,777,214 | Historic classful networks; now mostly treated as CIDR blocks. Includes many legacy /8 allocations. |
| B | 128.0.0.0 | 191.255.255.255 | 255.255.0.0 | /16 | 16,384 | 65,534 | Mid-sized historical networks; typical of early enterprise allocations. |
| C | 192.0.0.0 | 223.255.255.255 | 255.255.255.0 | /24 | 2,097,152 | 254 | Small classful networks; many early small-business assignments followed this pattern. |
| D | 224.0.0.0 | 239.255.255.255 | N/A | Multicast | N/A | N/A | Multicast-only; not used for unicast hosts. |
| E | 240.0.0.0 | 255.255.255.254 | N/A | Reserved | N/A | N/A | Reserved for future or experimental use; not normally routed. |