Learn networking, practice, and verify every result.
A structured networking library with connected guides and interactive tools for subnetting, IPv4, IPv6, routing, DNS, and diagnostics.
Not a list of articles: a learning path.
Topics are grouped by intent and technical relationship so you can progress from fundamentals to operations and security without losing context.
Understand the foundation
Start with architecture, OSI/TCP-IP, Ethernet, addressing, and protocols to build a solid mental model.
Open fundamentals →02Practice subnetting
Move from CIDR and masks to FLSM, VLSM, ranges, broadcast addresses, and subnet planning with real calculators.
Learn subnetting →03Connect the layers
Continue into switching, routing, services, troubleshooting, and security to understand networks end to end.
Continue with routing →9 clusters for learning networking layer by layer.
Networking fundamentals
Core concepts, architecture, layers, Ethernet, devices, media, topologies, and protocols.
Open cluster →IP addressing
IPv4, IPv6, and the concepts that connect addressing to network design.
Open cluster →Subnetting
Subnets, FLSM, and VLSM as a practical IPv4 planning cluster.
Open cluster →Switching and Layer 2
Ethernet switching, VLANs, trunks, STP/RSTP, link aggregation, and inter-VLAN routing.
Open cluster →Wireless access
Fundamentals and operation of WLANs based on the IEEE 802.11 family.
Open cluster →Routing and IP connectivity
Layer 3 decisions: routing tables, static routes, OSPF, NAT/PAT, BGP, FHRP, and route summarization.
Open cluster →Network services
Operational services including DHCP, DNS, NTP, SNMP/Syslog observability, and QoS.
Open cluster →Network troubleshooting
Diagnostic methodology, operating-system commands, and packet analysis with Wireshark.
Open cluster →Network security
Segmentation and defense: ACLs, VPN/IPsec, firewalls, AAA, and Layer 2 controls.
Open cluster →Calculate, convert, and validate without leaving the explanation.
Tools are connected to the guides so you can verify a concept immediately after learning it.
FLSM Subnet Calculator
Split an IPv4 network into equal-size subnets with FLSM. Calculate the new prefix, mask, block size, ranges and capacity for each subnet.
Open tool →Subnetting and CIDRVLSM Calculator
Design variable-size IPv4 subnets from host requirements. Calculate the smallest suitable prefix, allocate ranges in order, and reduce address waste.
Open tool →Subnetting and CIDRCIDR / Host Calculator
Convert host requirements into CIDR prefixes, or a prefix into usable address capacity. Optionally calculate the IPv4 network, broadcast, block size and host range.
Open tool →Subnetting and CIDRIs This IP Inside a Subnet?
Check whether an IPv4 address belongs to a CIDR network, normalize the network address, and inspect the exact block boundaries.
Open tool →Conversion and IPv6IPv6 Subnet Calculator
Split an IPv6 allocation into child prefixes, calculate the number of available subnets, and preview any section of the resulting prefix space by index.
Open tool →Diagnostics and public networkDNS Lookup: Query Public DNS Records
Query public A, AAAA, CNAME, MX, TXT, NS, PTR, SOA, SRV and CAA records with TTL data through a server-side DNS resolver.
Open tool →Less memorizing tables. More understanding what is happening.
SubnetMaster combines technical explanations, examples, and calculation tools so an answer is not only correct: you can also explain why.