Network Troubleshooting

CompTIA Network + Domain:

Domain 5.0: Network Troubleshooting and Tools

CompTIA Network + Objective:

Objective 5.1: Explain the network troubleshooting methodology.
Objective 5.1: Given a scenario, use the appropriate tool. 

Overview

Networks are important to business processes, and when they are not fully operational, it is costly and frustrating to the users. Network administrators need to understand not just how to keep the network functional but also how to approach troubleshooting problems when a network is not fully operational. This lab will review troubleshooting and a methodology that will provide ideas on where to start in the problem-solving effort. This methodology will be used as a guide in troubleshooting two protocols widely used in networks, and it is important to be able to diagnose issues with them. Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP) are the two protocols we will focus on in this exercise.

outcomes:

In this lab, you will learn to:

  1. Use the problem-solving process to troubleshoot a suspected DNS issue using CLI utilities and resolve the issue.
  2. Configure an operational DHCP scope of addresses.
  3. Observe the effects of a deactivated DHCP scope and resolve the problem.
Courses

Key terms and descriptions

Domain Name Service (DNS)
the protocol used to resolve and map hostnames and domain names into IP addresses on the Internet. DNS uses UDP port 53 for initiating requests. Name servers, or DNS servers, are servers that contain databases of associated names and IP addresses and provide this information to resolvers (hosts) on request.
nslookup
a utility used to perform query testing of DNS servers and obtain detailed responses at the command prompt. This information can be useful for diagnosing and solving name resolution problems.
Dynamic Host Configuration Protocol (DHCP)
protocol used to automatically assign network configuration parameters to devices on a network. Parameters include IP address, subnet mask, default gateway, server addresses such as DNS, and lease time. DHCP uses port number 67 to communicate from client to server and port 68 from server to client.
DHCP Scope
the consecutive range of possible IP addresses that the DHCP server can lease to clients on a network or subnet. Scopes typically define a single physical subnet on your network to which DHCP services are offered. Scopes are the primary way for the DHCP server to manage distribution and assignment of IP addresses and any related configuration parameters to DHCP clients on the network.
Command Line Interface (CLI)
a text-based method of accessing the shell of an operating system. Usually, CLI provides a more powerful, direct way of executing programs and utilities.
Universal Resource Locator (URL)
the named address of a resource on the Internet
Fully Qualified Domain Name (FQDN)
the complete domain name for a specific computer, or host, on the Internet. The FQDN consists of two parts: the hostname and the domain name.
ipconfig
The ipconfig command is used to view or modify a computer’s IP addresses, to release and then renew the IP address, and to flush the DNS resolver cache.
Ping
used to verify basic TCP/IP connectivity to a network host.
APIPA (Automatic Private IP Addressing)
A Microsoft Windows feature used when there is a failure in DHCP servers, allowing DHCP clients to obtain IP addresses. APIPA allocates IP addresses in the private range 169.254.0.1 to 169.254.255.254 and are displayed in ipconfig /all as autoconfiguration IPv4 addresses. When the DHCP server is operational, clients correctly update their addresses automatically.