Network Tools

These tools run locally in your browser. Do the reasoning first, use a tool to verify it, then solve a similar problem without help. Inputs and practice statistics stay on your device when browser storage is available.

Choose the right tool

If you want to…	Use…	Best after…
See how IPv4 bits form an address	Binary Trainer	IPv4 structure
Check network, broadcast, and host ranges	Subnet Calculator	Your own subnet calculation
Convert CIDR prefixes and masks	CIDR/Mask Trainer	The subnet mask reference table
Practise service ports and protocols	Port Trainer	Ports & Services
Classify private and special-use addresses	IPv4 Classifier	IPv4 address ranges

Binary TrainerConvert IPv4 octets between decimal and binary and make bit weights visible.Use it to understand address structureOpen toolSubnet CalculatorCheck network, broadcast, host ranges, masks, and the intentional /31 and /32 cases.Use it after your own calculationOpen toolCIDR/Mask TrainerPractise converting prefixes and dotted-decimal masks in both directions.Use it to automate the basicsOpen toolPort TrainerConnect a service with its port number and transport protocol.Use it while learning service troubleshootingOpen toolIPv4 ClassifierExplain private, public, loopback, link-local, multicast, and reserved ranges.Use it to check an address typeOpen tool

A reliable practice method

1. Write down your expected result.
2. Enter the values into the tool.
3. Compare the first differing step, not only the final answer.
4. Generate a new problem with a similar prefix or service.
5. Solve it again without the tool.

Binary TrainerIPv4 Subnet CalculatorCIDR/Mask TrainerPort TrainerIPv4 Address Classifier

Binary Trainer and IPv4 converter

Convert complete IPv4 addresses into four 8-bit octets or back again. Then practise individual octets with randomly generated challenges.

IPv4 ↔ binary

Input Convert

An IPv4 address has 32 bits: four octets of eight bits each. Binary input accepts dotted octets or one continuous 32-bit sequence.

Practise individual octets

Practise decimal ↔ binary conversion with bit weights, separate correct/incorrect counts, and locally stored statistics.

New challengeReset

Answer Check

IPv4 Subnet Calculator

Calculate the IP, prefix, mask, wildcard, network, broadcast, and host range—including the technical meaning of /31 and /32.

IPv4 address Prefix Calculate

CIDR/Mask Trainer

Practise prefixes and subnet masks in both directions with correct, incorrect, and streak statistics.

New challengeResetAnswer Check

Port Trainer

Practise HTTP, HTTPS, DNS, DHCP, SSH, FTP, SMTP, POP3, IMAP, RDP, SNMP, and NTP in both directions, including TCP/UDP.

Neue AufgabeReset

Answer Check

IPv4 Address Classifier

Classify private/public unicast, loopback, link-local, multicast, broadcast, and reserved ranges without outdated class-based logic.

IPv4 address Classify

What the result means

Subnet results

• Network is the first address of the calculated block and identifies the subnet.
• Broadcast is the final address of a classic IPv4 subnet and targets all hosts in that broadcast domain.
• First/last host show the conventional assignable range. /31 point-to-point links and /32 host routes are intentional exceptions.
• Wildcard is the bitwise inverse of the subnet mask. Some ACL and routing syntaxes use it; it is not another subnet mask.

The calculator validates one address and prefix. It cannot tell you whether a subnet overlaps your real design or whether a gateway and DHCP pool are consistent.

Address classification

“Private” means an address belongs to an RFC 1918 range; it does not mean the host is trusted or secure. “Public” means the address is not one of the handled special ranges; it does not guarantee that it is assigned, reachable, or safe. Documentation ranges such as 192.0.2.0/24 are for examples and must not be treated as Internet targets.

Service-port results

A registered or well-known port is a convention, not proof that a service is running. Applications can listen on different ports, firewalls can filter them, and an open TCP connection does not prove that authentication or application logic works. Diagnose the complete flow: source, destination, protocol, port, and application response.

Limitations and safe use

• Results are calculated locally and are not a scan of your network.
• Do not paste credentials, customer addresses, or confidential topology data into learning notes.
• Verify important production designs independently and have them reviewed.
• Test ports only on systems you own or are explicitly authorised to assess.