Cody Oncken

Series

Read in order, or jump to what hurts

Each series is a ladder. Beginner pieces assume nothing and define every acronym; advanced pieces assume the ones before them and do not re-explain fundamentals.

01

Beginner

Networking from First Principles

The stack explained without hand-waving. Start here if a VLAN is still an abstraction.

5 articles
  1. 01 What Actually Happens When You Open a Web Page Beginner 6 min
  2. 02 IP Addresses, Subnets, and Why /24 Isn't Magic Beginner 4 min
  3. 03 VLANs: One Switch, Many Networks Beginner 5 min
  4. 04 Routing, Gateways, and the Default Route Beginner 5 min
  5. 05 DHCP and DNS: The Two Services Everything Assumes Beginner 6 min
02

Beginner to Intermediate

Switching and the Campus LAN

What a switch actually does with a frame, and why loops, uplinks, and power budgets decide whether the campus stays up.

4 articles
  1. 01 How a Switch Learns: MAC Tables, Flooding, and Aging Beginner 4 min
  2. 02 Spanning Tree Without Fear Intermediate 5 min
  3. 03 Link Aggregation, Redundancy, and Why One Uplink Is a Bet Intermediate 4 min
  4. 04 PoE: Budgets, Classes, and the AP That Won't Boot Beginner 4 min
03

Beginner to Advanced

Enterprise Wi-Fi

From channels and airtime to OFDMA, BSS coloring, and multi-link operation.

6 articles
  1. 01 Wi-Fi Basics: Bands, Channels, and Widths Beginner 4 min
  2. 02 Why Your Wi-Fi Is Slow: Airtime, Not Bandwidth Beginner 4 min
  3. 03 Reading a Site Survey Intermediate 3 min
  4. 04 Deterministic RF Tuning for High-Density Wi-Fi 6 Advanced 6 min
  5. 05 Deterministic RF Tuning for High-Density Wi-Fi 7 Advanced 5 min
  6. 06 Roaming in Practice: 802.11k, v, and r Intermediate 4 min
04

Beginner to Advanced

Segmentation and Security

Trust boundaries, stateful filtering, 802.1X, and what inspection really costs.

6 articles
  1. 01 Trust Boundaries: Why a VLAN Is Not a Security Control Beginner 4 min
  2. 02 From Flat to Segmented: Migrating a Live Network Intermediate 4 min
  3. 03 Object-Based Networking and Policy Micro-Segmentation Advanced 5 min
  4. 04 802.1X Dynamic VLAN Assignment and RADIUS Advanced 6 min
  5. 05 Cryptographic Interception and SSL/TLS Inspection Advanced 4 min
  6. 06 DNS as a Security Control Intermediate 4 min
05

Intermediate

Operations and Automation

Documentation, read-only auditing, change windows, and the multicast problem nobody warns you about.

4 articles
  1. 01 Documentation That Survives You Intermediate 4 min
  2. 02 Read-Only API Auditing Intermediate 3 min
  3. 03 Change Windows and Blast Radius Intermediate 4 min
  4. 04 Multicast Optimization and IGMP Snooping in AV-over-IP Advanced 6 min
06

Intermediate

Static Routing and the Multi-Site Network

From the routing table to a second campus: static routes, summarization, site links, and the failure modes that come with them.

5 articles
  1. 01 The Routing Table, Line by Line Intermediate 4 min
  2. 02 Static Routes: Right Tool, Common Trap Intermediate 4 min
  3. 03 Designing a Second Campus Intermediate 5 min
  4. 04 Routing Between Sites: Fiber, VPN, and the UniFi Reality Intermediate 5 min
  5. 05 When Routes Break: Verification and Troubleshooting Intermediate 4 min
07

Intermediate

Packet Analysis

Reading a capture instead of guessing. tcpdump, Wireshark, and the five patterns that explain most tickets.

5 articles
  1. 01 Capturing at the Right Point Intermediate 4 min
  2. 02 Reading a TCP Handshake and Its Failures Intermediate 4 min
  3. 03 DNS and DHCP in a Capture Intermediate 4 min
  4. 04 TLS and QUIC in a Capture Intermediate 3 min
  5. 05 Five Patterns That Explain Most Tickets Intermediate 4 min
08

Intermediate

DNS, DHCP, and Core Services

The two services every other service assumes, at the depth a production network needs.

6 articles
  1. 01 Resolution, Step by Step Intermediate 4 min
  2. 02 Zones, Records, and Delegation Intermediate 4 min
  3. 03 DHCP in Depth Intermediate 4 min
  4. 04 IPAM and Naming That Scale Intermediate 4 min
  5. 05 High Availability for Core Services Intermediate 4 min
  6. 06 Core Services Failure Modes Intermediate 4 min
09

Intermediate to Advanced

Firewalls and Policy Engineering

Zones, state, NAT, and the discipline of a rulebase you can defend in an audit.

5 articles
  1. 01 Zones, Rules, and the Order That Matters Intermediate 4 min
  2. 02 State Tables and Connection Tracking Intermediate 4 min
  3. 03 NAT Without the Mystique Intermediate 4 min
  4. 04 Writing Policy You Can Defend Intermediate 4 min
  5. 05 Auditing a Live Rulebase Advanced 4 min
10

Intermediate

VPNs and Remote Access

IPsec, WireGuard, TLS tunnels, and where zero trust actually replaces a VPN.

6 articles
  1. 01 What a VPN Actually Buys You Intermediate 3 min
  2. 02 IPsec Without the Acronym Soup Intermediate 3 min
  3. 03 WireGuard in Practice Intermediate 3 min
  4. 04 TLS VPNs and Client Access Intermediate 3 min
  5. 05 Split Tunneling and the Return Path Intermediate 4 min
  6. 06 When Zero Trust Replaces VPN Advanced 3 min
11

Advanced

WAN, SD-WAN, and the Internet Edge

Circuits, BGP at the edge, SD-WAN claims versus reality, and QoS where the bill is.

5 articles
  1. 01 Circuits, Diversity, and Failover Advanced 3 min
  2. 02 BGP at the Edge Advanced 3 min
  3. 03 What SD-WAN Actually Solves Advanced 3 min
  4. 04 NAT, CGNAT, and the Edge Advanced 3 min
  5. 05 QoS Where It Counts Advanced 3 min
12

Intermediate

Monitoring and Observability

Everything you need to know what the network is doing, from SNMP to alert design.

6 articles
  1. 01 What to Measure and Why Intermediate 3 min
  2. 02 SNMP, Still Intermediate 3 min
  3. 03 Logs and Flow Data Intermediate 3 min
  4. 04 Metrics, Logs, Traces Intermediate 3 min
  5. 05 Alert Design People Trust Intermediate 3 min
  6. 06 Dashboards That Answer Questions Intermediate 3 min
13

Beginner

Physical Layer and Cabling

Copper, fiber, testing, and the rack standards that make everything above them maintainable.

5 articles
  1. 01 Copper Standards and Reality Beginner 2 min
  2. 02 Fiber Types and Connectors Beginner 3 min
  3. 03 Testing and Certification Beginner 2 min
  4. 04 Cabling for PoE Beginner 2 min
  5. 05 Racks, Labeling, and Standards Beginner 2 min
14

Intermediate

QoS and Real-Time Traffic

Classification, queuing, and why voice breaks at 07:55 while everything else looks fine.

6 articles
  1. 01 Why QoS Exists Intermediate 2 min
  2. 02 Classification and Marking Intermediate 3 min
  3. 03 Queuing and Shaping Intermediate 2 min
  4. 04 Voice Intermediate 2 min
  5. 05 Video and Screen Sharing Intermediate 3 min
  6. 06 Wireless QoS and WMM Intermediate 3 min
15

Advanced

Network Programmability

NETCONF, RESTCONF, YANG, and Python that changes a network safely.

6 articles
  1. 01 Models Before Protocols Advanced 3 min
  2. 02 NETCONF, RESTCONF, and YANG Advanced 2 min
  3. 03 Ansible for Network Devices Advanced 2 min
  4. 04 Python Libraries Worth Using Advanced 2 min
  5. 05 Validating Configuration Advanced 2 min
  6. 06 GitOps for Networks Advanced 3 min
16

Intermediate

UniFi Playbooks

The controller, end to end: adoption, VLANs, zones, Wi-Fi, switching, and the settings that bite.

6 articles
  1. 01 The Controller and Its Backups Intermediate 4 min
  2. 02 Networks, VLANs, and DHCP Intermediate 4 min
  3. 03 Firewall Zones and Policies Intermediate 4 min
  4. 04 Wi-Fi and PPSK Intermediate 3 min
  5. 05 Switching, Ports, and PoE Intermediate 3 min
  6. 06 Firmware, Updates, and Rollback Intermediate 3 min

Planned

What comes next

Written in the same shape, published only when the whole series is ready.