IP Address
Classify IP addresses by class (A-E) and identify public/private status
How to use IP Address
- 1Enter an IPv4 address, e.g. 192.168.1.10.
- 2Read its class (A/B/C), whether it is private or public, and its subnet mask.
- 3Use the details to plan addressing or troubleshoot connectivity.
IP address classification
Class by first octet: 1–126 A, 128–191 B, 192–223 C, 224–239 D (multicast)IP classification groups addresses by their first octet to indicate network vs host bit allocation and intended use.
Private ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are reserved for local networks and are not routable on the public internet.
Frequently asked questions
Is 192.168.x.x public?
No; it is private and only reachable inside your local network unless NAT is used.
What is a loopback address?
127.0.0.0/8 (notably 127.0.0.1) refers to the host itself for testing.
Why do we still use classes?
We mostly don't; CIDR replaced classful routing, but class helps understand legacy ranges.
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