Overview
As a
software tester, you must know the basic commands and tools to control a network errors,
you need it to save time (waiting for the IT staff to answer the ticket that
you opened 3 days ago is not a good option...) and even more important, if you
know how to make a good troubleshooting, you will know how to create such
errors as part of your testing matrix.
I hope that
this list will help you to achieve better testing matrix, and control the
architecture of your testing software.
Ipconfig
Probably the
most important commands that you can use when troubleshooting a network
connectivity issues. This command will provide the most basic TCP/IP network
information for a specific host (IP, Hostname, and Gateway Etc.).
The
information that provided by this command is sometimes known to the end user (depends
on the addresses configuration policy, that used suggest “Static”/”Dynamic”
configuration).
In addition,
this command can also use to manipulate the TCP/IP values, when used with
specific switches suggest:
/Renew –Renew the TCP/IP configuration for a
given adapter (when configured against a ‘Dynamic’ DHCP server, will not work
against static configuration).
/Release –
send request to the
DHCP server to release the current TPC/IP configuration for all/specific
adapter/s.
/Flushdns
- resets the
configuration of a DNS cache for a specific adapter.
Ping
The ping
utility, is probably the most common tool that used for network
troubleshooting. This utility, is used to provide a clear and fast connectivity
test between two hosts (Host that send the request against the Host that need
to respond).
When you
run the ping command, the connection between the hosts is performed with a
protocol called “Internet Control Message Protocol (ICMP)”, this protocol can
send echo packets to the destination host and wait for a response (The number
of the returned packets, and the timelines of the response, are the factors
that determines the connectivity strength between two hosts).
Note!
To access
the ping utility, you should open the “Command Prompt”, the basic way to do it:
Start > Programs > Accessories >
Command Prompt.
Tracert
Traceroute, is a utility which can help you to gain information (Involved devices Delays
between the devices, Etc.) about the packets that sent between two computers
(Requester -> Destination).
When
running this command, you will see the entire journey of a sent packet, the
results will be a display of all the devices it passes through. There are two available answers:
1. The
user receives the entire root (Computer A -> Computer B)
2. The
user receives the last device that host the packet, and the root computer will
not be accessible (Computer A -> Router (a Last device that host the
packet)).
Based on my
short review, you can see the real benefits of this command, think about a
computer or a website that you failed to access without any real reason.
When you
run this command you will get the specific location that stuck the
communication and will allow you to focus on one problematic device instead of
checking 10 others.
Netstat
The main
feature of this command is to provide the current state of the active network
connections on a given host. The returned information contains simple data that
explain the current status of the host against the network (Services, Used ports,
remote connected hosts Etc.).
Pathping
I love to
use this command, it combines the best from both Ping/Tracert commands (Information
and Functionality), and display the results on one centralized location that
really helpful when you want to see the full picture.
The most
important data that this command can return is the devices involved between the
source and destination, latency issues, and the amount of lost packets (if any)
between the objects.
Route
This simple
command should be used on two basic cases, the first case is when you want to
see the information about the HOST routing table, and second, when you want to
manipulate the table values.
Nslookup
The next
story will demonstrate the importance of this command:
When I
leaned my MCPD certificate my teacher explained to us, that more than 40% from
the network troubleshooting is relevant to DNS server, after I finished the
course and started my first job I saw that he was wrong, the real % was more
the 70%.
Got it? Now
listen…
The
Nslookup command (Win and UNIX), is used when you want to query a specific
Domain Naming system (DNS). Using such queries, you can make a basic
troubleshooting or get a specific set of information about the name resolving
architecture (address Mapping (Host/IP), Default DNS Servers, MX records for
exchange mail server…).
In addition, Nslookup supports two different modes:
Interactive - provide the option to query DNS server’s information about a number of
attached hosts/domains or simply print the list without an additional
specification.
Non-interactive -Provide the option to print the names and information of the requested
name (Domain / Host).
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