Addressing, in four directions
These four tools handle addressing at different layers: where an IP is and who hosts it, how many addresses a CIDR block actually contains, converting between range and CIDR notation, and identifying a device's manufacturer from its MAC address.
IP Lookup — geolocation and hosting
IP Lookup returns geolocation (country, region, city estimate), ASN, and hosting/ISP information for any IP address.
When to use it: identifying the rough location and provider behind a visitor or attacker IP, verifying a server's IP resolves to the expected datacenter region, or initial triage during a security investigation.
Reading results: geolocation accuracy varies — country-level is usually reliable, city-level is often approximate, especially for mobile or VPN traffic. Combine with the ASN and hosting provider fields for a fuller picture than location alone gives you.
Subnet Calculator — sizing a CIDR block
Subnet Calculator takes a CIDR block (like 192.168.1.0/24) and calculates the network address, broadcast address, usable host range, and total address count.
When to use it: planning subnet allocation before configuring a network, quickly checking how many usable hosts a given block actually provides, or verifying a firewall rule or routing table entry covers the range you intended.
Reading results: the usable host range is always 2 less than the total addresses in the block — the first address is the network address, the last is the broadcast address, and neither can be assigned to a host. A /31 is a special case for point-to-point links where both addresses are usable.
IP Range — converting range to CIDR
IP Range converts between a start-end IP range (e.g. 192.168.1.10 – 192.168.1.50) and CIDR notation, in both directions.
When to use it: converting a range from a hosting or cloud provider into CIDR blocks for firewall rules, checking how many individual IPs a given range contains, or translating CIDR into a plain range for documentation or non-technical stakeholders.
Reading results: an arbitrary range often can't be expressed as a single CIDR block, so it gets broken into the smallest set of blocks that exactly covers it. More blocks in the output means the original range didn't align neatly to power-of-two boundaries — that's expected, not an error in the tool.
MAC Lookup — identifying the manufacturer
MAC Lookup looks up the Organizationally Unique Identifier (the first three octets) of a MAC address to identify the manufacturer of the network device.
When to use it: identifying unknown devices on a network by their MAC address, verifying a device claiming a specific manufacturer actually has a matching OUI, or general network inventory and troubleshooting.
Reading results: a "locally administered" MAC (second character of the first octet is 2, 6, A, or E) means the address was manually set or randomized — common with VMs, containers, and modern phones or laptops doing MAC randomization for privacy — and won't return a manufacturer match. That's expected behavior, not an error.
How these fit together
IP Lookup and MAC Lookup answer "what is this" for two different address types on two different layers (network vs. link layer). Subnet Calculator and IP Range answer "how big is this block" from two directions — one starts from a CIDR, the other starts from a plain range — so which one you reach for depends on which format you already have in hand.