How do I check if an IP address is in a valid subnet range?

Use the Subnet Calculator to enter the network CIDR block and then compare the IP address against the computed network address and broadcast address to determine if it falls within the range.

Which ports are reserved and should not be used?

Ports 0-1023 are well-known ports reserved for system services (HTTP: 80, HTTPS: 443, SSH: 22). Ports 1024-49151 are registered ports. Use ports 49152-65535 for custom applications to avoid conflicts.

How do I validate a domain name format?

A valid domain name consists of labels separated by dots, where each label is 1-63 characters of letters, digits, or hyphens, does not start or end with a hyphen, and the full name does not exceed 253 characters.

Validate Network Configuration Online

Network configuration errors — incorrect subnet masks, invalid IP addresses, wrong port numbers, and misconfigured domain names — can take down services and are often discovered only after deployment. devtoolkit.sh brings the essential validation tools for network configuration into one place. Calculate subnet ranges and verify CIDR blocks, validate IP address format and range, look up port number assignments to avoid conflicts, and check domain name format before configuring DNS. Whether you are setting up cloud infrastructure, configuring firewalls, or debugging connectivity issues, these tools help you catch configuration mistakes before they reach production.

🌐Subnet Calculator

Calculate network address, broadcast, hosts, and subnet mask from IP/CIDR notation.

✓IP Address Validator

Validate IPv4 and IPv6 addresses with class, scope, and private/public detection.

⬡Port Number Reference

Searchable reference of well-known TCP/UDP port numbers and their services.

🔗Domain Name Validator

Validate domain names against RFC 1035 rules: length, characters, labels, and TLD.

FAQ

How do I check if an IP address is in a valid subnet range?: Use the Subnet Calculator to enter the network CIDR block and then compare the IP address against the computed network address and broadcast address to determine if it falls within the range.
Which ports are reserved and should not be used?: Ports 0-1023 are well-known ports reserved for system services (HTTP: 80, HTTPS: 443, SSH: 22). Ports 1024-49151 are registered ports. Use ports 49152-65535 for custom applications to avoid conflicts.
How do I validate a domain name format?: A valid domain name consists of labels separated by dots, where each label is 1-63 characters of letters, digits, or hyphens, does not start or end with a hyphen, and the full name does not exceed 253 characters.