IP Address Lookup
Validate and analyze IPv4 addresses.
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This IP Address Lookup checks whether an address is written correctly, tells you whether an IPv4 address belongs to a private or public range, and shows its four parts in binary. It is a network analysis aid for students, support staff and anyone configuring a router; it does not look up the location, internet provider or owner of an address.
What the analysis shows
Enter one address, such as the placeholder 8.8.8.8, and press Analyze. A home router address gives:
Valid IPv4 address: 192.168.1.10
Type: Private / reserved
Binary: 11000000.10101000.00000001.00001010Google's public DNS resolver, 8.8.8.8, is reported as Public with the binary form 00001000.00001000.00001000.00001000. An impossible address like 256.1.1.1 is rejected, because each of the four numbers must be between 0 and 255.
Ranges marked "Private / reserved"
| Range | Typical use |
|---|---|
| 10.0.0.0 – 10.255.255.255 | Large company and cloud networks |
| 172.16.0.0 – 172.31.255.255 | Office networks, Docker defaults |
| 192.168.0.0 – 192.168.255.255 | Home Wi-Fi routers |
| 127.0.0.0 – 127.255.255.255 | Loopback, "this computer" |
The first three are the private blocks set aside by RFC 1918. They can be used by anyone inside a local network but are never routed on the public internet, which is why millions of homes can all use 192.168.1.1 for their router at the same time.
Special addresses the tool still calls "Public"
Only the four ranges above are recognised, so several other non-public blocks are labelled Public. Knowing them helps with troubleshooting:
- 100.64.0.0 – 100.127.255.255 is shared address space for carrier-grade NAT (RFC 6598). If your router's WAN address falls here, your provider is sharing one public IP among many customers, and port forwarding for a CCTV recorder or game server won't work from outside.
- 169.254.x.x is link-local. A Windows or Mac computer gives itself one of these when it can't get an address from the router's DHCP server, so seeing it usually means a connection problem.
- 224.0.0.0 and above are multicast and reserved addresses, and 0.x.x.x means "this network"; none of them identify an ordinary device.
Why the binary form is useful
Subnetting only makes sense in binary. A /24 network, mask 255.255.255.0, fixes the first 24 bits: 11000000.10101000.00000001 for 192.168.1. Any address whose first three octets match, such as 192.168.1.10 and 192.168.1.200, is on the same subnet and can talk directly. To convert single octets back and forth, use the Binary Decimal Converter.
IPv6 and other limits
IPv6 addresses such as 2001:4860:4860::8888 are checked with a simple pattern and reported as valid, without classification or binary output. Mixed forms like ::ffff:192.168.1.1 and addresses with a zone suffix such as %eth0 are rejected. Leading zeros in IPv4 (010.1.1.1) are accepted here, but some software reads them as octal, so avoid writing addresses that way. The address you type is analysed in your browser and not looked up anywhere.