Chapter 6 of 6 · Cisco CCNA 200-901 DEVASC
Network Fundamentals
MAC and IP addressing, VLANs, devices, planes, IP services, ports and troubleshooting for DevNet Associate.
- 6topics
- 30 minfast track
- 1diagrams and exhibits
- 15%of the exam
Topics in this chapter
Take them in order, or jump to the one you need.
- 1MAC Addresses and VLANsLearn what MAC addresses do, how switches forward frames with them, and how VLANs split a network into broadcast domains with…5 min
- 2IP Addresses, Subnets, Routes and GatewaysLearn IPv4 and IPv6 addresses, subnet masks and prefix lengths, routing tables and default gateways, and how a host decides where…5 min
- 3Network Components and Reading a Topology DiagramLearn what switches, routers, firewalls and load balancers do, and how to read a basic network topology diagram with its links…Diagram5 min
- 4IP Services: DHCP, DNS, NAT, SNMP and NTPLearn what DHCP, DNS, NAT, SNMP and NTP do, how each one works, which ports they use, and the IOS XE commands used to configure…5 min
- 5Management, Data and Control Planes and Common Port ValuesLearn the management, control and data planes of a network device, and the common port numbers for SSH, Telnet, HTTP, HTTPS…5 min
- 6Diagnosing Connectivity Issues and Network ConstraintsDiagnose application connectivity problems caused by NAT, blocked ports, proxies and VPNs, and see how latency, jitter and packet…5 min
About this chapter
What this chapter covers
This chapter gives the networking background that every DevNet candidate needs, even though the exam is about code.
It covers addressing at Layer 2 and Layer 3, VLANs, the devices that make up a network, how to read a topology, the three planes of a device, the common IP services, port numbers and how to diagnose a failing application.
You are not expected to configure a full network. You need to understand it well enough to automate it and to find faults.
How the topics fit together
A packet starts at a host, crosses devices that each do a different job, and reaches a service on a port.
The first two pages cover addressing. MAC addresses and VLANs work inside a network, and IP addresses, subnets, routes and gateways work between networks. The third page names the devices and shows how to read a diagram that links them.
The fourth page covers the IP services that support every host. The fifth page splits a device into management, control and data planes, and lists the port numbers that identify each protocol. The last page puts it all to work by tracing a failure and showing how latency and loss affect an application.
Many API faults turn out to be network faults. A wrong VLAN, a blocked port or a DNS problem looks like a broken service.
How to use these pages
Each topic page has the same shape, so you can skim for what you need.
- What it is: the idea in plain words.
- How it works: the mechanism, with diagrams and example commands.
- What to remember for the exam: the facts to memorise.
- Common mistakes: the classic traps.
- Check yourself: three questions to test your understanding.
Learn the port numbers and the roles of the devices by heart. Both come up again and again, in this chapter and in the API chapters. If you can, practise with a simulator or a small lab, and run ping, traceroute and nslookup against your own systems.
Ready for more practice?
The full Cisco CCNA 200-901 DEVASC question bank has 808 questions, with timed practice exams and an explanation for every answer.
This study guide is independent and is not affiliated with, endorsed by, or sponsored by Cisco. Vendor names, certification names and exam codes are trademarks of their respective owners and are used for identification only.