traceroute: UDP, ICMP, and TCP Modes Explained
Three probe types down one four hop path, the packets on the wire for each, and the ICMP rate limit that makes a perfect path look broken.
Labs
Hands-on Cisco IOS XE lab walkthroughs. Each lab ships with a real CML topology, configs you can paste, and verified show output. Articles tagged Labs cover the full CCNA 200-301 blueprint across Network Fundamentals, Network Access, IP Connectivity, IP Services, and Security Fundamentals.
Latest posts — page 4
nmcli and nmtui: Managing Connections from the CLI
Devices against connection profiles, the activation step everybody forgets, and how to make a configuration survive a reboot.
ethtool: Link Speed, Duplex, Offloads, NIC Stats
The driver layer below the kernel: link settings, offloads that make packet captures disagree with the wire, rings, and where host-side drops show up.
ifconfig, route, netstat: Legacy net-tools to iproute2
The full command map, and the same host through both toolsets so you can see exactly what the legacy tools hide from you.
ARP on Linux: ip neigh, arp, and Neighbor States
The six-state neighbor machine walked live on a real lab, the tunables behind it, and why arp -n cannot show you any of it.
ip route: Managing the Linux Routing Table
Every field in a route line, get against show, blackhole routes, the replace gotcha, and policy routing with multiple tables.
The Linux ip Command: The Complete Guide
The grammar, the four objects you use every day, the output modifiers that make it readable, and how to create interfaces out of nothing.
IPv6 Transition Mechanisms: Which One, and When
Dual-stack, tunneling, and translation each solve a different IPv6 migration problem. This decision guide shows you which mechanism fits which situation and how the three fit together on real networks.
NAT64 Explained: Stateful, Stateless, and the DNS64 Half of the Story
How NAT64 lets an IPv6-only client reach an IPv4-only server: the full stateful configuration on Cisco IOS XE 17.18, the address synthesis math done by hand, the DNS64 half that makes it usable, and an honest platform finding from the lab.
IPv6 over IPv4 Tunnels: Manual, GRE, and 6to4 Compared
Configure a manual IPv6-over-IPv4 tunnel on Cisco IOS XE 17.18, prove it with a real ping across an IPv4-only core, and compare the three tunnel types you need to know: manual, GRE, and 6to4.
IS-IS for IPv6: Multi-Topology and the Single-Topology Trap
IS-IS runs a single topology by default, forcing IPv6 down the IPv4 shortest path even where IPv6 is broken. See how multi-topology IS-IS fixes the black hole, with real adjacency output on Cisco IOS XE 17.18.
EIGRP for IPv6: Classic and Named Mode on IOS XE
EIGRP for IPv6 is a separate protocol instance with no network statement and link-local next hops. You walk the classic interface-based config on IOS XE 17.18, see real adjacencies and routes, and clear up the shutdown gotcha.