Address Input
Invalid IP address format
IP Class & Type Detector
Use this tool to instantly identify the class of any IPv4 address (A through E) or the scope and type of any IPv6 address. Paste any IP and get a full breakdown — leading bits, default subnet mask, address purpose, and reachability scope — in one click. Ideal for CCNA, Network+, and day-to-day network troubleshooting.
IPv4 Class A–E
IPv6 Scope Detection
Leading Bit Analysis
Private vs Public
How to Use the IP Class & Type Detector
What This Tool Does
By analyzing the leading bits of any IP address, this tool identifies how routers and network hardware categorize that address — whether it's a routable unicast address, a private range, a multicast group, or an experimental block. For IPv4 it returns the legacy class (A–E); for IPv6 it returns the modern scope type (Global Unicast, Link-Local, Unique Local, Multicast, or Loopback).
Step-by-Step Instructions
- 1Enter an IP Address: Type or paste any IPv4 address (e.g.,
172.16.0.1) or IPv6 address (e.g.,fe80::1) into the input field. - 2Click Detect Properties: The tool reads the leading bits of the first octet (IPv4) or hex group (IPv6) and classifies the address.
- 3Review the Results: Check the class or type, default mask, leading bit pattern, purpose, and reachability scope in the results table.
Exam Tip: Class D and E addresses have no default subnet mask — Class D is reserved for multicast (
224.0.0.0–239.255.255.255) and Class E for experimental use (240.0.0.0–255.255.255.255). This is a common CCNA question.IPv4 Class Reference
| Class | First Octet Range | Leading Bits | Default Mask | Purpose |
|---|---|---|---|---|
| A | 1 – 126 | 0xxxxxxx | 255.0.0.0 /8 | Large networks, ISPs |
| — | 127 | 01111111 | — | Loopback (reserved) |
| B | 128 – 191 | 10xxxxxx | 255.255.0.0 /16 | Mid-size enterprise networks |
| C | 192 – 223 | 110xxxxx | 255.255.255.0 /24 | Small networks, home routers |
| D | 224 – 239 | 1110xxxx | N/A | Multicast groups |
| E | 240 – 255 | 1111xxxx | N/A | Experimental / reserved |
Frequently Asked Questions
What determines the class of an IPv4 address?
The class is determined entirely by the leading bits of the first octet. A first bit of 0 means Class A (1–127). Starting with 10 means Class B (128–191). Starting with 110 means Class C (192–223). This binary logic let early routers classify addresses without consulting a routing table — before CIDR made the system obsolete.
Why doesn't IPv6 use classes?
IPv4 classful addressing was notoriously wasteful — a single Class A block allocated 16 million addresses regardless of need. IPv6 replaced the system with a hierarchical prefix and scope model: addresses are assigned in variable-length blocks, and scope (Link-Local, Site-Local, Global) tells routers how far an address should be forwarded, without wasting space.
What are the default masks for each IPv4 class?
In classful networking the default masks are: Class A uses 255.0.0.0 (/8), Class B uses 255.255.0.0 (/16), and Class C uses 255.255.255.0 (/24). Class D and E have no default mask — they are not divided into host and network portions because they are not used for standard unicast traffic.
What IPv6 types does this tool detect?
The tool detects five IPv6 categories: Global Unicast (starts with 2 or 3 — internet routable), Link-Local (starts with fe80 — single subnet only), Unique Local (starts with fc or fd — private, like RFC 1918 for IPv4), Multicast (starts with ff), and Loopback (::1).
Is classful addressing still used on the internet?
No. The modern internet has used CIDR (Classless Inter-Domain Routing) since 1993, which assigns prefixes of any length regardless of the first octet. However, classful concepts remain essential for IT certification exams (CCNA, Network+, CompTIA) and for understanding how older Cisco IOS commands and RIPv1 behave by default.