Networking

How data gets from one device to another — across a desk, a building or the world. The concepts every network engineer uses daily, and the vocabulary that flies around on day one in a network operations team.

21 pages 150 glossary terms CCNA Network+

How to use this topic

The pages follow the path a packet takes: from the idea of a network and the layered models that describe it, through cables, Ethernet and switches, to IP addressing, routing and the services that make a network usable — DNS, DHCP and NAT. The last pages cover what keeps a network running in practice: monitoring and logging, wireless, security, troubleshooting and automation. Ansible and infrastructure as code beyond the network are covered in Infrastructure as Code & Automation.

Read them in order if networking is new to you; each page also works as a reference when a term comes up in a meeting or a ticket. Where a configuration makes an idea concrete, pages show short examples in Cisco IOS, the style used on the CCNA exam. Address calculations are shown with Python's ipaddress module, so every worked subnetting example is checked.

Pages marked CCNA and Network+ cover material from the Cisco CCNA (200-301) and CompTIA Network+ exams.

Learning path

  1. 01What Is a Network?What a computer network is, the kinds of networks from LAN to WAN, how they are laid out, and how their performance is measured.BeginnerCCNANetwork+
  2. 02The OSI and TCP/IP ModelsThe layered models that describe how data travels through a network, and how each layer wraps the data of the layer above it.BeginnerCCNANetwork+
  3. 03Cabling and the Physical LayerHow bits travel as electricity, light or radio: copper and fiber cables, connectors, categories, distances and Power over Ethernet.BeginnerCCNANetwork+
  4. 04Ethernet and MAC AddressesThe dominant technology for wired local networks: Ethernet frames, MAC addresses, duplex and speed.BeginnerCCNANetwork+
  5. 05Network DevicesWhat hubs, switches, routers, firewalls, access points and load balancers do, and at which layer each one works.BeginnerCCNANetwork+
  6. 06Switching and VLANsHow a switch learns where devices are, how VLANs split one switch into several networks, and how Spanning Tree prevents loops.IntermediateCCNANetwork+
  7. 07IPv4 AddressingHow IPv4 addresses are built, what the subnet mask does, which ranges are private or special, and what a default gateway is for.BeginnerCCNANetwork+
  8. 08SubnettingDividing an IPv4 network into smaller subnets, step by step, with worked examples you can check yourself.IntermediateCCNANetwork+
  9. 09IPv6 BasicsWhy IPv6 exists, how its addresses are written and shortened, the main address types, and how hosts configure themselves.IntermediateCCNANetwork+
  10. 10ARP and ICMPHow a host finds the MAC address that belongs to an IP address, and how ICMP reports errors and makes ping and traceroute possible.IntermediateCCNANetwork+
  11. 11Routing BasicsHow routers move packets between networks: the routing table, static and default routes, and longest prefix match.IntermediateCCNANetwork+
  12. 12Dynamic Routing and OSPFHow routers learn routes from each other: distance vector versus link state, administrative distance, and the basics of OSPF.AdvancedCCNANetwork+
  13. 13TCP, UDP and PortsThe two main transport protocols, how TCP makes delivery reliable, and how port numbers let many applications share one address.BeginnerCCNANetwork+
  14. 14DNSHow the Domain Name System turns names into addresses: the hierarchy, resolvers, record types and caching.BeginnerCCNANetwork+
  15. 15DHCPHow devices get an IP address automatically: the DORA exchange, leases, scopes and DHCP relay.BeginnerCCNANetwork+
  16. 16NAT and PATWhy network address translation exists, how static NAT, dynamic NAT and PAT differ, and what they mean for troubleshooting.IntermediateCCNANetwork+
  17. 17Operational Services: NTP, SNMP and SyslogThe services that keep a network observable: synchronized time with NTP, monitoring with SNMP, and logging with syslog.IntermediateCCNANetwork+
  18. 18Wireless NetworkingHow Wi-Fi works: the 802.11 standards, frequency bands and channels, access points and controllers, and wireless security.IntermediateCCNANetwork+
  19. 19Network Security BasicsProtecting a network: access control lists, firewalls, segmentation, VPNs, port security and 802.1X.IntermediateCCNANetwork+
  20. 20Troubleshooting Tools and MethodA structured way to find network problems, and the command-line tools that show what is really happening.IntermediateCCNANetwork+
  21. 21Network AutomationManaging networks with code instead of by hand: controllers and SDN, REST APIs and JSON, and tools such as Ansible.AdvancedCCNANetwork+

Networking glossary

Short definitions of the terms used in this topic. The full glossary covers every topic.