Asad Ijaz
Lead Networking Architect and Editor at NetworkUstad. CCNP and CCNA certified, with 10+ years of experience in enterprise network design, implementation, and troubleshooting. Writes practical tutorials on routing, IPv4 management, network automation, and security fundamentals.
TCP vs UDP: Transport Layer Protocols Explained
TCP and UDP are the two primary transport layer protocols handling data communication between hosts on an IP network. TCP is connection-oriented; UDP is connectionless. That single distinction cascades into almost every other difference between them — reliability, ordering, flow control, and overhead all follow from that one design choice. TCP: Connection-Oriented and Reliable Transmission...
The Transport Layer Explained: Process-to-Process Delivery, TCP, UDP, and Beyond
We routinely run multiple applications on a single device at once — a browser, an email client, a video call — and each needs its data delivered to the right place without interference from the others. The transport layer, Layer 4 of the OSI model, is what makes this possible: it accepts data from the...
IPv6 Subnetting Explained: Structure, Worked Examples, and Best Practices
IPv6 subnetting works differently from IPv4 subnetting. There is no address shortage to manage, so the goals change. Instead of squeezing every possible host out of a block, IPv6 subnetting is about building a clean addressing hierarchy. This guide walks through the address structure, a full worked example, LAN and WAN allocation, and the troubleshooting...
Subnetting Example with a /16 prefix – Exclusive How To Guide
In many situations, we require a large number of subnets. For example, the class B network address 130.20.0.0 has a default mask of 255.255.0.0 or /16 Prefix. So, this address has 16 network bits in the network portion and 16 host bits in the host portion. The 16 bits in the host portion are available...
Classful vs. Classless Addressing: What’s the Difference?
Classful and classless addressing describe two different ways to structure an IPv4 address. Classful addressing came first, in the early internet of the 1980s. It used fixed Class A, B, and C ranges. That rigid structure eventually led to serious IPv4 address exhaustion. CIDR arrived in 1993 and introduced classless addressing instead, allowing flexible prefixes...
Introduction to Subnetting: How and Why to Divide a Network
Subnetting lets a network administrator divide a large network into smaller, more manageable sub-networks by borrowing bits from the host portion of an IP address. Rather than running one enormous flat network, subnetting adds a third level to the addressing hierarchy, network, subnetwork, and host, giving administrators far more control over how a network actually...
Ping and Traceroute: The Essential Network Troubleshooting Toolkit
Ping and traceroute are the first tools most network engineers reach for when something isn’t working. Both rely on ICMP, but they answer different questions: ping tells you whether a destination is reachable at all, while traceroute maps out exactly which hops a packet passes through along the way. This guide covers both in depth,...
ICMPv6 Neighbor Discovery: RS, RA, NS, and NA Messages Explained
ICMPv6 does considerably more than its IPv4 counterpart. Beyond basic error reporting, it absorbs an entire protocol’s worth of functionality through the Neighbor Discovery Protocol (NDP), four distinct message types working together to replace ARP, handle address resolution, and drive SLAAC. This guide covers each of the four NDP message types, how they interact, and...
Internet Control Message Protocol (ICMP) Explained
IP is deliberately unreliable: it has no built-in mechanism to report when something goes wrong. That’s exactly the gap the Internet Control Message Protocol (ICMP) fills. It doesn’t make IP more reliable, it doesn’t retransmit or guarantee delivery, but it does report problems back to the source, which is what makes tools like ping and...
The EUI-64 Process: How IPv6 Interface IDs Are Generated
When a device configures an IPv6 address through Stateless Address Autoconfiguration (SLAAC), it gets the network prefix, typically a /64, from a Router Advertisement, but it has to generate its own 64-bit Interface ID independently. This guide covers exactly how that generation works: the EUI-64 process that derives an Interface ID from a MAC address,...