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CCNA lab 3 of 46

Client IP settings and TCP versus UDP on a Linux host

Work a help-desk ticket from the client side: read and renew a Linux laptop's IP settings, test reachability and name resolution, then capture a TCP handshake and a UDP DNS exchange to see the difference on the wire.

Run this lab

It needs Lite: its 4 nodes are set to 4 vCPU and 3,584 MB in total. That fits the free demo too.

In your workspace: Shared, then CCNA 200-301 guided labs, then 03 - Client IP settings and TCP versus UDP on a Linux host

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Level
Beginner
Time
About 50 minutes
Nodes need
4 vCPU, 3,584 MB
Smallest plan
Lite

The scenario

A help-desk ticket has arrived at Northfield Accounting: "My new Linux laptop says it's connected, but I can't get to the file server." Before you can fix tickets like this, you need to read a client's IP settings fluently, on Linux and on the Windows and macOS machines your users also have, and know what normal looks like on the wire.

The office LAN uses DHCP from the router R1, which is also the office DNS server. R1's Loopback0 plays the file server files.office.lab (10.3.20.10). The laptop is H1 (Alpine Linux). PC1 is a desk PC with a static address.

DeviceInterfaceAddressConnects to
R1Gi0/110.3.10.1/24 (gateway, DHCP and DNS server)S1 Gi0/0
R1Loopback010.3.20.10/24 (files.office.lab)–
S1VLAN 110.3.10.2/24–
H1eth0DHCP (pool OFFICE, from .50)S1 Gi0/1
PC1eth010.3.10.20/24, gateway 10.3.10.1S1 Gi0/2

Topology: R1 Gi0/1 — S1 Gi0/0 · S1 Gi0/1 — H1 · S1 Gi0/2 — PC1.

What you’ll practise

  • Read a client's address, mask, gateway and DNS settings on Linux, and name the Windows and macOS equivalents
  • Release and renew a DHCP lease and match it to the server's binding
  • Test reachability with ping, traceroute and the ARP cache
  • Resolve names with nslookup and explain the search domain
  • Capture and explain the TCP three-way handshake and a UDP request/response with tcpdump

The tasks

  1. Read the laptop's IP settings
  2. Renew the lease and find it on the server
  3. Test reachability and read the ARP cache
  4. Resolve names
  5. Watch a TCP connection being made
  6. Watch a UDP exchange
  7. Put TCP and UDP side by side

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Client IP settings and TCP versus UDP on a Linux host4 nodes, 3 links. Every link is listed as text below the diagram.R1S1H1PC1Gi0/1Gi0/0Gi0/1eth0Gi0/2eth0
4 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/1 to S1 Gi0/0
  • S1 Gi0/1 to H1 eth0
  • S1 Gi0/2 to PC1 eth0
Nodes in Client IP settings and TCP versus UDP on a Linux host, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 1,024 MB
S1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 1,024 MB
H1Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB
PC1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CCNA 200-301 guided labs.

  3. Open 03 - Client IP settings and TCP versus UDP on a Linux host and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.