You have a CIDR and need the actual range
Someone hands you 10.0.0.0/22 and asks how many addresses that is, or what the broadcast address is. Doing the bit math in your head is how off-by-one firewall rules get written.
Compute the block
The CIDR / Subnet Calculator takes an IPv4 CIDR and returns the network address, broadcast address, total and usable host counts, and the first and last usable addresses. Paste the block, read the range, and write the rule with confidence.
Context from the host part
When you also need to know what a specific IP in that range resolves to or how it is formed, the URL Parser is not the tool — but knowing the network boundaries first keeps your IP-based logic honest. Start with the subnet, then reason about individual hosts.
Useful for
- Writing firewall or security-group rules.
- Sizing a VLAN or a private address plan.
- Explaining a CIDR to someone who thinks in counts, not masks.