Transcript Chapter 17

Chapter 17: Troubleshooting Tools
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Chapter 17 Objectives
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The Following CompTIA Network+ Exam Objectives Are
Covered in This Chapter:
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4.2 Given a scenario, analyze and interpret the output of
troubleshooting tools
• Command line tools
o ipconfig
o netstat
o ifconfig
o ping/ping6/ping -6
o tracert/tracert -6/traceroute6/traceroute -6
o nbtstat
o nslookup
o arp
o mac address lookup table
o pathping
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Protocol Analyzers
Used to capture packets in their raw
format as they cross the network.
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Throughput Testers
Work much like a protocol analyzer in that they
measure the traffic seen on the network and
can also classify the types of traffic that are
eating up bandwidth
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Connectivity Software
Designed to allow you to make a connection to
the machine, see the desktop, and perform
any action you could perform if you were
sitting in front of it.
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Command Line Tools
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Most of us are running Transmission Control
Protocol/Internet Protocol (TCP/IP) Version 4 on our
networks these days so we absolutely need a way to
test IP connectivity.
We also need be able to test and verify IPv6 networks.
Several utilities to verify TCP/IP function on Windows
workstations for both IPv4 and IPv6
The utilities are fairly platform independent and most of
them can now use both IPv4 and IPv6.
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Command Line Tools
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traceroute / tracert
– Traceroute (trace for short) displays the path a packet
takes to get to a remote device by using
• Time-To-Live (TTL)
• Time-outs
• Internet Control Message Protocol (ICMP) error messages
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Command Line Tools
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ipconfig and ifconfig
– The utilities known as ipconfig (in Windows), and
ifconfig (in Unix/Linux/Mac) will display the current
configuration of TCP/IP on a given workstation
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Current IP address
DNS configuration
Windows Internet Naming Service (WINS) configuration
Default gateway
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Command Line Tools
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IPConfig Options
– Ipconfig /all
– Ipconfig /release
– Ipconfig /renew
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To release your current
DHCP TCP/IP
information in Vista,
you must elevate your
command prompt
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Command Line Tools
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The ping Utility
– Ping is the most basic TCP/IP utility, and it’s included with
most TCP/IP stacks for most platforms.
– In most cases, ping is a command-line utility, although
there are many GUI implementations available.
– You use the ping utility for two primary purposes:
• To find out if a host is responding
• To find out if you can reach a host
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Command Line Tools
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Address Resolution Protocol (ARP)
– The Address Resolution Protocol (ARP) is part of the
TCP/IP protocol stack.
– Uses broadcasts to translate TCP/IP addresses to MAC
addresses.
The ARP table in Windows includes a list of TCP/IP
addresses and their associated physical (MAC) addresses.
The ARP table contains two kinds of entries:
– Dynamic
– Static
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The arp Utility (using “arp –a”)
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Command Line Tools
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The nslookup Utility
– A command-line utility that allows you to perform a
single DNS lookup for a specific entity.
– The nslookup utility comes with Windows NT and later,
as well as most versions of Unix and Linux, but not
with Windows 95/98.
– It is run from a Windows command prompt.
– At the command prompt, you can start the nslookup
utility by typing nslookup and pressing <enter>.
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Command Line Tools
• The Mtr Command
– Mtr or My traceroute is a computer program that
combines the functions of the traceroute and ping utilities
in a single network diagnostic tool.
– Mtr is great if you have Linux or Unix, but by default, it’s
not installed on Windows devices.
– Third-party applications of Mtr are available to install on
Windows
– Microsoft includes its own version of Mtr called pathping
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Command Line Tools
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The Route Command
– The route command is used to employ both static and
default routing on Windows Vista and Server 2008
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Command Line Tools
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The nbtstat Utility
– Microsoft Windows uses an interface called Network
Basic Input/Output System (NetBIOS) relating names
with workstations
– It is an upper-layer interface that requires a transport
protocol—usually, TCP/IP, but IPv6 can be used as
well.
– Deploying the nbtstat utility will achieve these three
important things:
• Track NetBIOS over TCP/IP statistics
• Show the details of incoming and outgoing
NetBIOS over TCP/IP connections
• Resolve NetBIOS names
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NBTStat
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The nbtstat –a command:
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NBTStat
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The nbtstat –c command:
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NBTStat
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The nbtstat –n command:
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NBTStat
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The nbtstat –r command:
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NBTStat
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The nbtstat –S command:
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The nbtstat –s command:
The nbtstat –s command produces the same output as nbtstat –S except
it will also attempt to resolve remote-host IP addresses into host names.
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Command Line Tools
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The netstat Utility
– netstat is a great way to check out the inbound and
outbound TCP/IP connections on your machine.
– Packet statistics like how many packets have been sent
and received, the number of errors, etc. can be viewed.
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NetStat
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The netstat –a command:
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Command Line Tools
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File Transfer Protocol (FTP)
– FTP has become a cross-platform protocol for transferring
files.
– Windows TCP/IP stack includes a command-line ftp utility.
– To start the ftp utility, enter ftp at a command prompt.
– The result is an ftp command prompt:
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To display a list of all the commands you can use at the ftp
command prompt, type help or ? and press <Enter>
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Command Line Tools
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The Telnet Utility
– Part of the TCP/IP protocol suite,
– Telnet is a Terminal Emulation program designed
to be used over the network
– telnet allows you to make connections to remote
devices, gather information, and run programs.
– Telnet was originally developed to open terminal
sessions from Unix workstations to Unix servers.
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Command Line Tools
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Don’t Use Telnet, Use Secure Shell (SSH)
– Telnet is totally unsecure
– Telnet sends all data in clear text including your name
and password.
– It has to be really bad thing these days; consider
Microsoft doesn’t even enable it on their latest Oss
(you know it really must be unsecure)
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SSH is the tool to use.
SSH provides the same options as Telnet, plus a lot more
– It doesn’t send any data in clear text
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Your servers, routers, and other devices need to be
enabled with SSH.
SSH is not configured by default on most devices.
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Summary
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Summary
Exam Essentials Section
Written Labs
Review Questions
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