Guides
Network Engineering Guides
Practical, engineer-to-engineer walkthroughs — each paired with a free tool to put it into practice.
How to Subnet a Network: A Practical /24 Walkthrough
A step-by-step guide to IPv4 subnetting — CIDR notation, masks, host counts, and VLSM — with worked examples you can follow on a real /24.
Read guideWhat Is an ASN and How to Find the ASN for an IP Address
Understand Autonomous System Numbers, BGP announcements, and prefixes — and learn three ways to find which ASN owns any IP address.
Read guidePrefix Lists vs ACLs: A Multi-Vendor Guide
How prefix lists and access lists differ, when to use each, and how the syntax maps across Cisco IOS, Juniper, Palo Alto, and Fortinet.
Read guideReverse DNS Explained: PTR Records, in-addr.arpa, and Why It Matters
What reverse DNS is, how PTR records and the in-addr.arpa / ip6.arpa zones work, and why rDNS matters for email deliverability and logging.
Read guideHow to Share a Password Securely (Without Email or Slack)
Why emailing or messaging passwords is risky, what end-to-end encryption and one-time links actually do, and how to share a secret safely.
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