Addresses are the common currency of network work. An address shows up in a log, a ticket, a firewall rule or a mail header, and the questions are always similar: whose is it, how is it routed, roughly where is it used, which subnet does it belong to, and, on the LAN, which device has this hardware address?
The IP & Network Utilities answer those questions. IP Lookup identifies the owner and routing network, IP Geolocation estimates location, the Subnet Calculator does the CIDR arithmetic and MAC Lookup names the vendor of a network interface. My IP and ASN Lookup round out the set.
What these tools cover
- Ownership and routing of public addresses: RDAP records from the five regional registries (holder, range, CIDR, handle, dates, abuse contact), BGP origin ASN and announced prefix from Team Cymru, and reverse DNS.
- Approximate location: city, region, country and coordinates from a server-side copy of DB-IP City Lite, with anycast warnings and registration-country context.
- Subnet math: network, netmask, wildcard, broadcast, usable range, host counts and address scope for IPv4 and IPv6, in the browser.
- Hardware vendors: IEEE OUI lookup for MAC addresses, with detection of randomized (locally administered) and multicast addresses.
- Your own address and its network, and details of Autonomous Systems.
Private and special-use addresses are explained rather than looked up, and no tool attempts to identify people behind addresses.
Why they matter
- Correct filters. A wrong prefix or a whole provider range blocked by mistake causes outages; the right announced prefix or exact CIDR keeps rules tight.
- Effective abuse handling. Reports reach someone only when sent to the registry's abuse contact with the right handle.
- Honest location context. Fraud and geo-restriction decisions improve when the location is read together with owner and ASN.
- Faster LAN troubleshooting. Vendor and address type often identify an unknown device in seconds.
The tools at a glance
| Tool | What it does | Best for | Guide |
|---|---|---|---|
| IP Lookup | Who owns and routes an IP address — registry, ASN, range, abuse contact. | Look up any IPv4 or IPv6 address: regional registry, network owner, ASN, CIDR range, registration country, abuse contact and reverse DNS. | Guide |
| IP Geolocation | Approximate location of an IP address from a geolocation database. | Estimate where an IP address is used — city, region, country and coordinates on a world map — from the DB-IP Lite geolocation database, together with the network owner and routing. | Guide |
| Subnet Calculator | Calculate network ranges, masks and host counts. | Calculate network address, broadcast, usable host range, netmask and host count for any IPv4 or IPv6 CIDR block. | Guide |
| MAC Lookup | Look up the vendor of a MAC address. | Identify the manufacturer of a network interface from its MAC address using the IEEE MA-L (OUI) registry. | Guide |
Which tool should I use?
- "Who owns this IP and where do I report abuse?" → IP Lookup (guide).
- "Roughly where is this IP used, and is it anycast?" → IP Geolocation (guide).
- "Which addresses does 10.20.30.40/28 cover? How many hosts fit in a /26?" → Subnet Calculator (guide).
- "Which vendor made the device with this MAC? Is the MAC randomized?" → MAC Lookup (guide).
- "What is my own public IP?" → My IP (guide).
- "Who operates AS13335 and where is it registered?" → ASN Lookup (guide).
- "Convert a netmask, split a network or plan VLSM" → Subnet Mask Converter (guide).
Typical workflows
Responding to an attack source
- Look up the source address in IP Lookup: holder, announced prefix, ASN and abuse contact.
- Open the ASN in ASN Lookup to see whether it is a hosting provider, ISP or cloud.
- Check IP Geolocation for context only; do not rely on the city.
- Put the exact address or the announced prefix into a temporary block rule, checking its coverage in the Subnet Calculator, and send the report to the abuse contact.
Writing a tight allow-list
- Get your egress address from My IP (and check whether IPv6 is used as well).
- Decide on the smallest block that covers it; verify network, range and host count in the Subnet Calculator.
- Confirm with IP Lookup that the range belongs to your provider and not to a shared cloud range.
Finding an unknown device on a VLAN
- Take the IP and MAC from the DHCP lease or ARP table.
- Check with the Subnet Calculator that the IP is inside the expected VLAN range.
- Look up the MAC in MAC Lookup for the vendor, or recognize a randomized address.
Checking how your own range is seen
- Look up an address from your block in IP Lookup and compare holder, prefix and reverse DNS with your records.
- Open IP Geolocation to see where the database places it; if wrong, publish a geofeed and contact the database provider.
Related guides
- IP Lookup, IP Geolocation, Subnet Calculator, MAC Address Lookup.
- What is my IP and ASN Lookup.
- My Info & Identity tools – what your connection and browser reveal.
- Network Diagnostics – ping, traceroute, MTR, ports and speed.
- Conversion & Calculation tools – IP notation converters and subnet mask tools.
Frequently asked questions
What is the difference between IP Lookup and IP Geolocation?
Both pages show the same combined report. IP Lookup is organized around ownership: registry holder, CIDR range, BGP origin and abuse contact. IP Geolocation puts the approximate DB-IP location and map first, which is the right starting point when the question is where an address is used.
Which tools run in my browser and which use the server?
The Subnet Calculator runs entirely in your browser. IP Lookup, IP Geolocation, My IP and MAC Lookup use the NetTools server, which queries registries and public DNS resolvers or local copies of the DB-IP and IEEE databases.
Can I look up private addresses like 192.168.1.10?
Not in the lookup tools, because private and other special-use ranges have no public owner or location; the tools explain which range an address belongs to instead. The Subnet Calculator works with any address, including private ones.
How do I find who to contact about abuse from an IP address?
Use IP Lookup. It reads the RDAP record of the responsible regional registry and shows the abuse role contact with a copy button, along with the network handle to quote in your report.
How accurate are the locations?
Country is usually right, region often, city frequently wrong, especially for mobile, VPN, cloud and anycast networks. Locations describe a provider's address block, never a device or person.
Where do I split a network into smaller subnets?
The Subnet Calculator analyzes one CIDR block at a time. To split a network by count, host size or a VLSM plan, use the Subnet Mask Converter in the conversion tools.