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Showing posts from 2007

Address Resolution Protocol & Display ARP Cache On Computer

Address Resolution Protocol(ARP) finds Physical address(MAC Address) of a network host from IP address of that host. To communicate between two devices, source device must know the IP address and MAC address of the destination device. If the destination device does not have MAC address of the destination device, it sends ARP broadcast to find the MAC address of the network host belongs to the IP address. The device having the IP address(destination device) will respond to the source device with its MAC address. Source device will update ARP cache with the newly find MAC address of the destination device. ARP cache stores MAC address of the other network devices for the future use and periodically undergo flushing to avoid obsolete entries.

How to Display ARP cache On A Computer
To view the MAC address entries stored in ARP(Address Resolution Protocol) cache on your computer, follow the steps below.
Start Command Prompt

Type arp -a to display current ARP entries on your computer

PS: arp …

Getting Device Manager Error Code 10

If any device connected to your computer is not working properly, first step is to check its status in Device Manager (DM). This tutorial explains device manager error code 10 and the solution to fix it. It tells the device cannot be detected by the computer. Error code 10 comes with following message: This device is either not present, not working properly, or does not have all the drivers installed. (Code 10). Now let us check the normal troubleshooting steps to resolve it.

Standard Procedure to Fix Device Manager Error Code 10 Check Connectivity

If the hardware not connected properly, you will get this popup. So make sure the unit is connected properly.

Reseat the unit

It is an extension of first step. You just disconnect the device and reconnect it. Check if the issue persists. This procedure is easy for USB devices because they offer plug and play support. For example if you are using USB wireless adapter to connect your PC to a WiFi network and having the same problem, you may dis…

This Device is Not Configured Correctly. (Code 1)

If your computer is unable to configure a device, device manager (DM) will show you error code 1. The complete error code 1 is This device is not configured correctly. (Code 1) To update the drivers for this device, click Update Driver. If that doesn't work, see your hardware documentation for more information. This DM alert is self explanatory. By reading the message itself one can understand the real reason to get this alert. The message also suggests the most effective solution for device manager error code 1.

Solve Error Code 1 Update Driver

As the warning suggests, the first step to solve error code 1 is to update the driver. To learn how to update driver installed on your PC, click the link below.
How to update Driver

Remove the Device

If the updated unit failed to fix the problem, you may want to delete it from Device Manager (DM). After deleting the hardware, you can reconnect it using Add New Hardware Wizard from Control Panel.
If you are still getting error code 1 even afte…

Interior Gateway Routing Protocol (IGRP)

Interior Gateway Routing Protocol (IGRP)

IGRP is an interior gateway protocol

invented by cisco to replace the RIP.

It is a distance-vector routing protocol

used by routers to exchange routing data

within an autonomous system.

Important points
_______________ 1. IGRP supports multiple metrics for each

route, including bandwidth, delay, load,

MTU, and reliability

2.The maximum hop count of IGRP-routed

packets is 255 (default 100).

__________________ 1. IGRP is considered a classful routing

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Routing Information Protocol (RIP)

Routing Information Protocol (RIP) - CCNA Tutorials

The Routing Information Protocol (RIP) is a dynamic routing protocol.It is inside the network to create a routing table
which helps routers to understand the layout of the network with changes in network connections. RIP is an interior gateway protocol (IGP) using the distance-vector routing algorithm.

Working of Routing Information Protocol

RIP is a distance-vector routing protocol. It uses hop count as the routing metric. 15 is the maximum number of hops allowed in RIP. RIP sends routing-update messages at regular intervals and when the network topology changes.The normal RIP updation time is 30 seconds while the hold down time is 180 seconds. RIP is based on UDP and working on the Transport layer. Routing by RIP is also called routing by rumor.

RIP Stability Features

RIP implements following mechanisms to maintain the stability. They are:

1. Split horizon
2. Route poisoning
3. Holddown mechanisms

Different versions of RIP

The major…

Practical Uses of Netstat Command in Analyzing Connected Foreign Addresses

Netstat command is a DOS command used to find all active TCP connections between your computer and other network devices with port numbers and TCP connection state. By simply using this command on command prompt, you will get the list of active TCP connections between local IP address(your computer) and foreign IP addresses. You can also find the port numbers open in those connections. With proper syntax we can effectively use it to view how your computer is connected to foreign computers. It has many important uses in computer security. Check the image below to understand its simple use.

List of Common Netstat Command Syntax netstat -n : Displays addresses and port numbers in numerical form

netstat -a : Displays all connections and listening ports

netstat -b : Displays the executable involved in creating each connections or listening ports.

netstat -e : Displays Ethernet statistics

netstat -o : Displays the Process Identifier associated with each connection

netstat -p :Shows con…

Tracert- Tool to Find the Path of a Packet

Tracert command is used to determine the path from your computer to destination host by sending ICMP Echo Request messages. The path though which the packet traveled will be printed in the command prompt. ICMP command Tracert is very helpful to troubleshoot any kind of network related issues. It is used to determine the network location where the actual cause of the issue present in any kind of network related issues. It sends ICMP Echo messages to the destination host and decrement its TTL value by one when it pass on hop. When the packets pass each hop it display the path in DOS window and you can easily identify the route. This feature helps to identify the actual cause of any network issue. So it is a handy tool for every network Engineers to analyze and troubleshoot network issues. Let us check how to use this tool.

If you want to know the route of the server of from your computer, you can check it by typing following code on DOS prompt.

Tracert  www.corene…

Create Or Delete Windows User Account From Command Prompt

You can create a user account on your computer directly from Command Prompt by using the DOS command Net User. This command not only helps to create a new user account on a Windows computer but also helps to modify existing user account. This tutorial explains the use of the command net user and explains the procedure to create a new user account on a Windows computer. We also check how to modify an existing user account on a Windows computer using net user command.

Learn The Command Net user
Net user command is used to create, delete and edit user accounts on Windows computers from command prompt. Let us check different syntax to create, modify and delete user accounts from Command Prompt.

To create User Account:   net user Username Password /domain

To modify User Account:   net user Username Password /add /domain

To Delete User Account:   net user Username /delete /domain
While entering username from Command Prompt for a new user account, make sure it is maximum 20 character long.…

Wireless Range Expander- an introduction

The function of a wireless range expanter is to extend the
range of the wireless signal from a wireless router....

The pictorial representation of the working is given below.

Wireless router--------(45 feet)----------------pc

Let us think the range of the router signal is 45 feet.
The wireless adapter on the pc will receive the signal
from the router and will create a connection
between the wireless router and the pc.

If the distance between the pc and wireless router is
70 feet what can we do?

Ans. Establish a range expaner in between the router and the pc.

The range expander will receive signal from the wireless router
and extend the signal to a certain limit.

wireless router-----(40 feet)------range extender----(30 feet)------pc( wireless

Now the wireless computer will go online by receiving signal from range expander.

Detailed explanation will be in the following posts......
No:Recent TutorialsHow To Power Cycle a ModemSetup Linksys WRT54G Wireless Router3How to Configure …

Session layer and Its Importance in OSI Reference Model

Session layer is the fifth layer in OSI reference model. It responds to service requests from Presentation layer and issues service requests to Transport layer. The major function of the Session layer is to create, maintain and terminate sessions. Session layer is also responsible for finding and sending data across correct connection. To setup and tear down connection Session layer communicate with Transport layer. Major functions of Session layer are listed below.

The major functions of session layer are:
Starts and ends a session across a network Allows applications to share information. Ensures that information is flowing to the right place Communicate to presentation layer and Transport layer.
We can have multiple sessions on a network due to Session layer.

Eg: We are seeing a movie where sound and the seen both should match. It is one of the application of the Session layer. A list of protocols working in Session layer are listed below.

Major Session layer protocols
AppleTalk D…

Role of Transport Layer - Responsibilities and Protocols

Transport layer is the fourth layer in OSI Reference Model. It responds to service requests from Session layer and issues service requests to Network layer. Transport Layer is responsible for delivering messages between hosts. In Transport layer, data travels in the form of segments. Transport layer is responsible for creating an end to end connection between source IP and the destination IP. For establishing this end to end connection, Transport layer is using two major protocols TCP and UDP. TCP is connection oriented protocol where UDP is connection less protocol. So by using TCP we can create an end to end reliable connection between source and destination hosts. Transport layer is called host-to-host transport layer in TCP/IP model.

Duties of Transport layer
Major duties of Transport layer are:
Creating an end-to-end connection between hosts in different network, Error recovery, Flow control, Ensuring complete data transfer in TCP Congestion avoidance

The end to end connectio…

MAC Sublayer Defined in IEEE 802.3

During the development of IEEE Ethernet, IEEE divided Data Link layer in to two. They are MAC sub layer and LLC sub layer. MAC sublayer functions are performed in hardware and is the bottom part of data link layer. MAC sublayer is defined in IEEE 802.3. MAC sublayer defines how data is transmitted in an Ethernet environment and defines framing, MAC addressing etc. Let us check the functions of MAC sublayer in details below.

Major Functions of MAC Sublayer in IEEE Ethernet Defines how information is transmitted in an Ethernet environment

MAC Sublayer defines framing

This Sublayer defines the working of Ethernet and MAC addressing

CSMA/CD works in MAC Sublayer
How to Differentiate Ethernet II and MAC Sublayer Frames
We know Ethernet has two versions and it is important to know how to differentiate both versions of Ethernet. Major difference between Ethernet II (developed by DIX) and IEEE 802.2/3 is the frame value. If the frame value is greater than 1500, the frame is of Ethernet II. IEEE ve…

LLC (Logical Link Control) IEEE 802.2

In IEEE's version of Ethernet, the top sublayer of Data link layer is Logical Link Control(LLC). LLC's function is performed in software. LLC defines how to multiplex multiple network layer protocols in the data link layer frames. Logical Link Control sublayer performs its multiplexing by using Service Access Point (SAP) identifiers. Logical Link Control sublayer is defined under IEEE 802.2. There are two types of IEEE 802.2 frames. They are:
Service Access Point(SAP)

Subnetwork Access Protocol(SNAP)
Major Duties of Logical Link Control(LLC) Multiplex multiple network layer protocols in to frames

Sequencing and flow control

IEEE 802.2 uses SAP(Service Access Point) or SNAP(Subnetwork Access Protocol) field to differentiate between encapsulated layer 3 payloads. IEEE 802.2 (LLC) concerns Ethernet, Token Ring and FDDI. To read more about MAC sublayer, visit the link below.
MAC Sublayer IEEE 802.3

Though sequencing and flow control can be done in Logical Link Control Layer, normally t…

Data Link Layer Provide Physical Addresses

The second layer in OSI Reference model is Data Link Layer. Data link layer is responsible for providing physical addresses for the devices connected to the network. Physical address is also called hardware address because it is built in address (not a logical address like IP address). Data link layer is responsible for taking bits from Physical layer and convert them to frames. All communications done in Data link layer is in the form of frames.

Sub division in Data-link Layer
In IEEE version of Ethernet, Data link layer is subdivided in to:

1. Logical Link Control (LLC)
2. Media Access Control (MAC)

Data-link Layer devices

Networking devices functioning at Data link layer are:

Responsibilities of Data Link Layer
Define Physical Addresses Communication in the same network in form of FramesDefine hardware topology of the network
Major Data Link layer Protocols
CIF : Cells in Frames EthernetFDDI : Fiber Distributed Data InterfaceGARP : Generic Attribute Registration Pro…

Physical layer

Physical layer is the first layer in OSI model which deals with the physical transmission medium. The data transferred via physical layer is in the form of electrical signals. In a real life we can treat the physical layer as road where the vehicles are passing.Because the road is the one which is carrying the vehicles and linking the cities. Like that the physical layer is transmitting the data signal in the form of electrical signal and connecting nodes.

The major cables using in physical layer are:

1. Coaxial cable

2. Twisted pair cable

3. Optical fiber cable

Devices working in physical layer:

1. Internet gateway

2. Hub

3. Repeater

The major functions and services performed by the Physical Layer are:

1. Bit-by-bit delivery

2. Modulation

3. Encoding and Signaling:

4. Bit synchronization

5. Physical network Topology

In Physical Layer data is transmitting in the form of electric pulse and the cables are responsible for the safe delivery of the signals. Physical Layer is also responsible f…

OSI Reference Model

The International Organization for Standardization (ISO) developed a seven layer model called Open Systems Interconnection (OSI)Reference Model to help vendors and network experts to learn how data is transferred between networking devices. OSI Reference Model helps networking device manufactures to implement new network standards and policies. OSI Reference Model helps network administrators to reduce the complexity of networks and makes it easy to troubleshoot networking issues.

Seven Layers of OSI Reference Model
There are seven layers in OSI Reference Model and each layer has specific role in data communication. Seven layers of OSI reference model are listed below.

Physical layer

Data link layer

Network layer

Transport layer

Session layer

Presentation layer

Application layer

What is The Need of OSI Reference Model
Prior to the introduction of Open System Interconnection (OSI) Reference Model, each vendors have their own manufacturing standards. It forced the user to stuck with single ven…

Effective Use of Ping Utility

Ping is a network utility to check the connectivity between two nodes in a computer network. Ping sends ICMP packets to destination device and if the packets reach the destination successfully, source device will receive ICMP replies. If the ICMP packets failed to reach the destination, we will get ping packet loss reply. ICMP is the short form of Internet Control Message Protocol. To check the connectivity of a destination host, say a website, follow the instructions.
Open Command Prompt

type ping [Destination Address] and press enter.

Eg: ping

Practical Uses of Ping Command How to Change Default TTL Value Set On  Packets

 Transmit failed. General Failure

Automatically Set Continuous Echo Requests To a Destination Until We Manually Stop

How to Change Default Size of ICMP Echo Request On Your Computer(ping -l)

How to Check Optimium MTU Size Value Of Your Network

Packet Needs To Be Fragmented But DF Set -Reason and Solution

Tell Packets to Don't Fragment While in Test