Networking Tools
Use networking tools when you need to calculate ranges, convert masks, classify IP addresses, or prepare reverse DNS zones.
Search Networking Tools
Start With The Right Tool
Calculate A Network Range
Start here when you need usable host counts, subnet masks, network boundaries, or broadcast details.
Classify An IP Address
Use the IP checker when you need to confirm whether an address is public, private, or otherwise special-use.
Prepare Reverse DNS
Generate the correct reverse naming format before creating PTR records or reverse zones.
Featured Tools
Article Topic Hubs
Networking Articles
Learn IPv4 subnetting, CIDR notation, subnet masks, usable address ranges, private and public IP addresses, APIPA and reverse DNS fundamentals.
DNS Troubleshooting Articles
Troubleshoot DNS propagation, SPF, DKIM, DMARC, MX, delegation, reverse DNS and other common domain or email configuration failures.
Browse All Networking Tools
Networking Tools
Subnet Calculator
Calculate network range, usable hosts, subnet mask, broadcast address, and more.
Private vs Public IP Checker
Check whether an IPv4 address is private, public, or special-use.
CIDR ↔ Subnet Mask Converter
Convert between CIDR notation and dotted-decimal subnet masks.
Reverse PTR Zone Helper
Generate reverse PTR record format and suggested reverse DNS zone names.
Featured Articles
What Is APIPA? 169.254.x.x Explained
Learn what APIPA means, why devices assign 169.254.x.x addresses, what it says about DHCP problems, and how to troubleshoot a link-local IP quickly.
How to Fix SPF Softfail
A practical guide to fixing SPF softfail, including how to identify the sending domain, review the SPF policy, authorise senders, and tighten enforcement safely.
How to Check an MX Record
A practical guide to checking an MX record, reading priorities and targets, and confirming whether mail is routed to the provider you expect.
How to Fix DKIM Failures
A practical guide to fixing DKIM failures, including wrong selectors, missing records, bad key publication, and signing problems in email platforms.
How to Fix SPF PermError
A practical guide to fixing SPF PermError, including multiple SPF records, too many DNS lookups, syntax mistakes, and broken includes or redirects.
Private vs Public IP Addresses Explained
Learn the difference between private and public IP addresses, how special-use ranges fit in, and why correct IP classification matters in troubleshooting.