Network


29
Oct 09

How to clear DNS cache in windows ?

Sometimes browsing issues are created due to invalid DNS cache entries stored on your computer. To clear DNS cache follow the steps below:

1. Click start > Run> cmd. )In case of vista/win7 you can open command prompt respective way.
2. Type ” ipconfig /flushdns
3. Hit enter. This will show you message ” Successfully flushed the DNS resolver cache“.
4. Exit command prompt.

You can start restart the web browser. Now you can have no DNS issues with some websites which were not accesible earlier.


9
Oct 09

How to determine the corruption of winsock entries?

Winsock stands for windows sockets. Using winsock, applications connect to internet. When winsock.dll and its registry entries get corrupted you can’t access internet. But how will you determine that this error is of winsock ?

If you’re using windows xp then NETDIAG utility comes up with widows installation disk. Insert the CD into CD-ROM and find the “support/tools” folder. Double click the NETDIAG executable, complete the installation instructions. Once the installation is complete, open the command prompt. Type the following in command prompt.

netdiag /test:winsocks

This command after execution will return results for working of network components that include winsock. If you find any corruption with winsock then you’ve to repair the winsock entries.


7
Oct 09

How to find out IP Address of your own machine ?

IP Address is like address to your home on internet. People in network will identify your machine based on your IP Address. What is IP Address ? An IP address is a series of digits separated by dotted decimals and represented from 0.0.0.0 to 255.255.255.255. This is to identify machines in network. Never release your IP Address information to public forums or give it to anonymous people.

Here is the process to find out IP address of your machine from command prompt:

1. Go to start menu > Run > “cmd”.
2. Type “ipconfig /all” in command prompt.
3. You’ll find the IP Address in information under “ethernet adapter local area connection” or “PPP Adapter .

3rd party programs and websites

You can even find your IP Address from the 3rd party websites and programs. There are many to list here but i’ll restrict to few of them.

* IP2Location
* Trace My IP
* IP Address Report
* My IP Address
* WhatIsMyIPAddress
* IP Chicken


5
Oct 09

How to check which program is generating network traffic?

Some programs on windows access network and download files to update themselves. This is annoying in most cases other than anti-virus program. So how you’ll find out that which program is accessing internet ?

You can use following command in command-prompt:

netstat -b -n

and look for ‘ESTABLISHED’ connections.

You can even use following tools :

1. A Visual Netstat
2. Net Tools 5.0
3. Ethereal
4. AnVir Task Manager
5. Wireshark
6. IPTRAF (For linux)


22
Aug 09

How to check the ports in use?

You want to check if any ports are already in use or not. What will you do in such cases? Downloading heavy network monitoring apps are not always going to help if your need is limited and you’re interested in letting your resources taken up by such apps. So let’s see how you can do this with minimal efforts.

For windows:

1. Netstat: You can use NETSTAT command on command prompt. This will show you protocol statistics and all available TCP/IP connections.

You can use these commands in command prompt:

netstat

netstat -anb (a = all, n = don't do DNS lookup, b = list executables associated)

netstat -h (lists all the parameters )

2. TCPView
There is tiny utility which shows all the TCP/UDP/ connections. This utility is just 207kb and works with all versions of windows. You can download it here.

For Linux

1. Netstat command used under root can let you find out which hidden ports are used by which applications.

netstat –nap

or you can use

netstat –ntulp

For both windows and linux, you can use network monitoring program Wireshark. I know it is not worth to download huge apps for just lookup information. But i found out this application worthy to list here for reference.