IP Lookup

Use tool Favorite Add to Recent

Looks up the attributes of an IP address, supports IPv4 and IPv6, identifies address types such as public, private, loopback, link-local, and multicast, and calculates common network details like subnet mask, CIDR, network address, broadcast address, and usable host range

Introduction

The IP Lookup tool parses and inspects the attributes of any IP address, with full support for both IPv4 and IPv6. Once you enter an address, the tool automatically identifies its version and determines whether it is a public address, a private address (LAN/intranet), a loopback address, a link-local address, or a multicast address. For IPv4, it can also compute the subnet mask, network address, broadcast address, and usable host range when combined with a CIDR prefix.

This tool is especially useful for network administrators, system engineers, and developers who need to quickly understand the role and position of an IP address within a network. It is a handy assistant for troubleshooting network configuration and planning subnet divisions.

Technical Principles

Address-type detection is based on the special ranges reserved by IANA (the Internet Assigned Numbers Authority). Private addresses use 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16; loopback addresses use 127.0.0.0/8; and link-local addresses use 169.254.0.0/16. The tool classifies an address by comparing its leading bits against these ranges.

For subnet calculation, the IPv4 address is converted to a 32-bit integer and combined with the mask using bitwise AND (&) and OR (|) operations: the network address is the IP bitwise-ANDed with the mask, while the broadcast address sets all remaining host bits to 1. Under standard conditions, the usable host count is 2^(32-prefix) - 2 (subtracting the network and broadcast addresses). For IPv6, the tool expands and compresses addresses and classifies them by prefix ranges such as fc00::/7 (ULA) and fe80::/10 (link-local).

Use Cases

  • Network troubleshooting: determine whether an IP is public or private to quickly locate configuration issues
  • Subnet planning: enter a CIDR prefix to compute the subnet mask, network address, and usable host count
  • IPv4/IPv6 conversion: view both the expanded and compressed forms of an IPv6 address for comparison and recording
  • Security analysis: identify loopback, link-local, multicast, and other special addresses to help filter abnormal traffic
  • Teaching and demos: illustrate IP address classification and subnetting principles in networking courses
  • Configuration validation: verify address planning before setting up servers, firewalls, or routers

Frequently Asked Questions

Q: What is the difference between a public and a private address, and how do I tell them apart?
A: A public address is directly reachable on the internet, while a private address only works inside a local network. The tool automatically detects private ranges defined by RFC 1918 (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16); private addresses are not routed on the public internet.
Q: What does the CIDR prefix mean?
A: CIDR (Classless Inter-Domain Routing) uses a /prefix length to indicate how many consecutive leading bits in the subnet mask are 1. For example, 192.168.1.0/24 means the mask is 255.255.255.0 and supports 254 usable hosts. A larger prefix means a smaller subnet with fewer hosts.
Q: Does the tool support IPv6?
A: Yes. The tool can parse full IPv6 addresses, identify their type, and expand a :: compressed form into the full form or compress it back, making complex IPv6 address structures easier to understand.

Typical Usage

Query a private IPv4 address along with its subnet details:

Input IP: 192.168.1.10
Input CIDR: 24

Output:
  Address type: Private address (LAN/Intranet)
  CIDR range: 192.168.1.0/24
  Subnet mask: 255.255.255.0
  Network address: 192.168.1.0
  Broadcast address: 192.168.1.255
  Usable host range: 192.168.1.1 - 192.168.1.254
  Usable hosts: 254

Query an IPv6 address:

Input IP: fe80::1a2b:3c4d:5e6f:7089

Output:
  IP version: IPv6
  Address type: Link-local address
  Expanded form: fe80:0000:0000:0000:1a2b:3c4d:5e6f:7089
  Compressed form: fe80::1a2b:3c4d:5e6f:7089

Related Tools

This tool and My IP Address both belong to the networking category: My IP Address fetches your machine's egress IP, while this tool analyzes the attributes of any IP in depth. In web development and data interchange workflows, it is often used alongside URL Decode and URL Encode; for data handling, Base Convert and ASCII Lookup are also handy.

Back to list
TOP