How to reset user profile of a domain user in windows 7 ?

Hi,

It normally seen that user profiles on domain networks failed to load, or user can login but unable to perform any task, in other words you can say user profile become corrupt.
Mostly, IT professionals unjoined domain and joined again, some come up with fresh installations, these things can solve the issue but take too much time to make things available for user and in these case user's mostly lost few important data in such lengthy process.

Solution:

If you see above mentioned issues with the user either on Domain network or stand alone system, all you need to do is:
STEP-1
Login via Administrator ID
Goto Command Prompt. (cmd)
Type Regedit
Goto Hkey_Local_Machine\Microsoft\Software\Microsoft\WindowsNT\CurrentVersion\ProfileList
Then Locate the user with the corrupt profile, Right Click and press Rename and Add String "Problem" at the end. (Which help you finding this problematic profile later)
Log-Off

STEP-2
Login via user ID (which has problem)
You'll see that windows will configure new profile for the same user and take you to the New Desktop.
Goto Hkey_Local_Machine\Microsoft\Software\Microsoft\WindowsNT\CurrentVersion\ProfileList and Then replace the new profile name of the user with the old one.
Log-Off

STEP-3
Login with the user ID and you'll have the same Desktop with all the same settings and configurations. :)

The Above steps will not take more then 7 minutes to restore machine to the previous state. please ask if more information required.

OSI Reference Model

OSI Reference Model

(Open System Interconnection)

This model was established in 1970 by ISO. It is data communication model.
It is logical and conceptual model.
This model has 7 layers:
1. Application Layer
2. Presentation Layer
3. Session Layer
4. Transport Layer
5. Network Layer
6. Data link Layer
7. Physical Layer

1) Application Layer

Deals with the communication of software on different machines.
For example: HTTP, FTP, SMTP, Telnet and DNS servers, all operating systems, web browsers, communication software (messengers, Skype etc).

2) Presentation Layer

Three activities are taking place at this layer:
1) Encryption: The process of converting the plain text in to cipher text for data confidentiality is called encryption. i.e. DES, 3DES and AES
2) Translation: Coverts protocol from one form to other. Like IPX to IP and vise versa.
3) Compression: It simply works with the compression of data like win zip.

3) Session Layer

A time period in which two machines communicate is called a session.
This layer deals with:

• Session establishment: To establish a session before data communication.
• Session management: To manage the session throughout the communication.
• Session termination: To manually terminate the session or there is a network down.

4) Transport Layer

• It uses protocols to transfer data from one machine to another machine.
• Two protocols work on this layer, TCP/IP and UDP.

TCP/IP (Transmission control protocol/Internet protocol)

• It provides error recovery.
• It relies on IP for end-to-end delivery of data, including routing issues.

Functions of TCP/IP
1. Multiplexing using port number

• TCP identifies applications by their port numbers.
• Multiplexing relies on the use of a concept called a socket
• Socket consist of three things

1. IP address
2. Transport protocol (TCP or UDP)
3. Port number

• Multiplexing helps in running multiple applications on a machine. PC keeps every application separate and transfers data accordingly.
• Every application and protocol has port number.
• Port number identifies data that which application this data belong to.
• Like:

Telnet 23
SMTP 25
HTTP 80
HTTPS 443
DNS 53
Range of Port number is 1 – 65536.
1 – 1024 are already assigned.

2. Error recovery

• TCP numbers data bytes using the sequence and acknowledgement fields in the tcp header
• TCP sends data in sequence
• Sender also sends re-transmission timer.

3. Flow control using Windowing

• TCP implements flow control by taking advantage of sequence and acknowledgement fields in the TCP header.
• Window size is the number of packets sent before getting acknowledgement.
• It starts with smaller size of window than gradually increases until some error occurs.

UDP (user data gram protocol)

• It is connection less protocol.
• It also works at transport layer.
• It does not do any error recovery thus it takes less bandwidth.
• It perform
• Data transfer
• Data segmentation
• Multiplexing using port numbers

5) Network Layer

• It deals with the function of path selection and logical addressing
• The protocols use are:
• IP (internet protocol) in TCP/IP
• IPX in Novell
• DDR in AppleTalk
• Every network and host has IP address.
• Router works on this layer

IP define three different network classes:

• Class A 1-126
• Class B 128-191
• Class C 192-223

6) Data Link Layer

• This layer is divided into two sub-layers
• LLC Sub-layer: it create link between network and data link layer. For example ARP.
• Mac Sub-layer: it deals with error detection, addressing and orderly delivery of frames.
• Addressing: In many networks more than two devices are attached to the same physical network.
• Data link layer defines addresses to make sure that correct device listen and receive data.
• In Ethernet data link layer uses Media Access Control (MAC) address.
• It is 48-bit long address.
• It also performs error detection.
• It put a field of FCS (frame check sequence) in a frame. This field holds the value of CRC (cyclical redundancy check) algorithm.
• This CRC value is calculated by mathematical formula applied on data in the frame.
• Same value in generated on destination, if values are same than there is no error.
• It does not perform error recovery only error detection

7) Physical layer

• It is pure hardware layer of OSI model.
• On this layer frame is converted into bits.
• Hubs, repeaters and all cables work on this layer.

Data on different layers

• Data on Transport layer is called a segment.
• Data on Network layer is called a packet.
• Data on Data link layer is called a frame.
• Data on Physical layer is converted into bits.

INTRODUCTION TO NETWORKING

INTRODUCTION TO NETWORKING

COMMUNICATION MODES

1. Simplex (one way communication)
2. Half Duplex (two way communication but not simultaneously)
3. Full Duplex (two way communication simultaneously)

Duplex and Speed Mismatch Issue

This issue creates if any switch and NIC not have the same setting, due to this packets starts to drops.
Syntax:
Switch (config) #int fa0/1
Switch (config-if) #duplex full
Switch (config-if) #speed 100

Manufacturing Terms of Cisco

EOS (End of sale)
It is use for such product whose manufacturing become terminates, but is warranty is valid due to sold in market before.
EOL (End of life)
It is use for such product whose manufacturing as well as warranty become stop. So the Cisco does not support such device and consider as garbage.
IOS (Internetwork operating system)
It is the operating system use by router or layer-3 switches.
Examples: version 12.3, 12.2, 12.1, 12.0, 11.3

SWITCH

It is a device use for networking (LAN), they based on specific chip that is represented by ASIC (Application specific Integrated chip).

Modular Switch

Such switches in which we can add the additional cards when need.
Layer-2 Switches
Such switches which only do switching.
Examples: (CISCO Express 500) and (CISCO Catalyst 2940, 2950, 2960 series).
Layer-3 Switches
Such switches which can do switching as well as routing.
Example: (CISCO Catalyst 3550, 360, 370, 4500, 6500 Series).

ROUTER
It is a internetworking device (WAN), they based on microprocessor.

Cisco Switch And Router Hardware Components
1) RAM 2) NVRAM 3) FLASH 4) ROM

RAM
It is such memory where the running configuration (user configuration) exists.

NVRAM
It is such memory where the data stored permanently and this configured data is refer by the term “start-up-configuration”.

FLASH
It is such memory where the IOS present and here the data also present permanently.

ROM
It is such memory where all modes of switch or router exist, these modes called the ROM monitor mode; they come after the IOS load.

Switches and Routers boot sequence

• At Post point, the hardware is check.
• At Flash point, IOS files or IOS check.

Best Regards, 

S. N. Jafar

Lan Topologies

The shape of a network, and the relationship between the nodes in that network is known as the Network Topology. The network topology determines, in large part, what kinds of functions the network can perform, and what the quality of the communication will be between nodes.

Start Topology:
A star topology creates a network by arranging 2 or more host machines around a central hub. A variation of this topology, the 'star ring' topology, is in common use today. The star topology is still regarded as one of the major network topologies of the networking world. A star topology is typically used in a broadcast or SIMO network, where a single information source communicates directly with multiple clients. An example of this is a radio station, where a single antenna transmits data directly to many radios.

Ring Topology:
A ring topology (more commonly known as a token ring topology) creates a network by arranging 2 or more hosts in a circle. Data is passed between hosts through a 'token.' This token moves rapidly at all times throughout the ring in one direction. If a host desires to send data to another host, it will attach that data as well as a piece of data saying who the message is for to the token as it passes by. The other host will then see that the token has a message for it by scanning for destination MAC addresses that match its own. If the MAC addresses do match, the host will take the data and the message will be delivered. A variation of this topology, the 'star ring' topology, is in common use today.

Mesh Network:
A mesh topology creates a network by ensuring that every host machine is connected to more than one other host machine on the local area network. This topology's main purpose is for fault tolerance as opposed to a bus topology, where the entire LAN will go down if one host fails. In a mesh topology, as long as 2 machines with a working connection are still functioning, a LAN will still exist. The mesh topology is still regarded as one of the major network topologies of the networking world.

Bus Topology:
A bus topology creates a network by connecting 2 or more hosts to a length of coaxial backbone cabling. In this topology, a terminator must be placed on the end of the backbone coaxial cabling.
The bus topology is still regarded as one of the major network topologies of the networking world.

Best Regards,

S. N. Jafar

Network Cables

Straight through Cable: is a network cable that connects a computer to a network device. For example, straight through cables are cables that connect a computer to a network hub, network switch, and network routers. (To connect Different devices)
Color sequence in straight cables are:
1-White Orange
2-Orange
3-White Green
4-Blue
5-White Blue
6-Green
7-White Brown
8-Brown
Note: same color combination on both Ends of the cable
Cross-Over Cable: Networking cable that connects two computers or network devices directly to one another, crossover cables are used to connect two computers (or same devices) with network cards together without using a network hub, network router, or network switch.
Color sequence in cross-over cables are:
1-White Green
2-Green
3-White Orange
4-Blue
5-White Blue
6-Orange
7-White Brown
8-Brown
Note: just replace 1 with 3 and 2 with 6.
Roll-Over cable: Both the combination are opposite to each other like if, straight combination at one end than on the other end it must be opposite.
i.e. Used to connect router to PC.

Thanks.

S. N. Jafar

Network Communication Media

There are two mediums for network communication.
1-Cable Media (Guided Media)
2-Wireless Media (Un-guided Media) (will discuss later)

Cable Media (Guided Media)
i.e: co-axial cable, UTP (un-shielded twisted Pair), STP (Shielded Twisted Pair) and Fiber Optics.

Co-axial cable
Coaxial cables are a type of cable that is used by cable TV and that is common for data communications. Data is transmitted through the center wire, while the outer braided layer serves as a line to ground. Both of these conductors are parallel and share the same axis. This is why the wire is called coaxial!
There are two types of co-axial cables
1- Thin-net co-axial cable (Speed 10 Mbps, Range 185 meter)
2- Thick-net  co-axial cable (Speed 10 Mbps, Range 500 meter)

UTP (unshielded twisted pair)
Short form of Unshielded Twisted Pair cable, UTP cable is a popular cable used in computer networking that consists of two shielded wires twisted around each other. In the image to the right, is an example of the different network cables you’re likely to encounter.
UTP cables are twisted to cancel the EMI (Electro-magnetic interference), it has four pairs which are twisted so that magnetic and electric fields are opposite and it cancels EMI.

Given below is the Categories of UTP:

CAT 1                     Used for only voice communication
CAT 2                     Used for only voice communication
CAT 3                     Data + Voice both, Speed 4 Mbps, Range 100m
CAT 4                     Data + Voice both, Speed 10 Mbps, Range 100m
CAT 5                     Data + Voice both, Speed 100 Mbps, Range 100m
CAT 6                     Data + Voice both, Speed 1000 Mbps, Range 100m
CAT 6A                  Data + Voice both, Speed 10 Gbps, Range 10 to 15 meter

STP (Shielded Twisted Pair)
Short form of Shielded Twisted-Pair cable, STP is a cable originally developed by IBM for Token Ring that consists of two individual wires wrapped in a foil shielding to help provide a more reliable data communication.

FIBER OPTIC CABLE:
In fiber optic cables data transmit in the form of light only. There are two types of fiber optic cables which are:

1- Single Mode Fiber:
In single mode fiber, light inject through a Laser and only single ray of light travels on theory of total internal reflection (Stimulated Emission)
Maximum Bandwidth/Data rate on fiber cable   = 40 Gbps (Giga-bps)
Range ( after which signal drops)                              = up to 1 k.m (on 10 Gig)

2- Multi Mode Fiber:
In multi mode fiber, Light inject through LED ( Light Emitting Diode) and so many rays can travel simultaneously on total internal reflection (Spontaneous Emission Theory)
Maximum Bandwidth/Data rate on fiber cable   = 10 Gbps (Giga-bps)
Range ( after which signal drops)                              = 500 m

Best Regards,

S. N. Jafar

Types of Network

There are two types of Network
1- Distributed Network: which is costly and its even hard to troubleshoot. its also not easy to manage these type of networks. for example if we have three different locations of our office than we need to have a data center on all three locations which would be synchronized to Head Office in respective time period (Scheduled)  see below the diagram of Distributed Network. For Big organizations distributed network is highly not recommended.
2-Centralized Network: In a centralized network design, every branch is directly connected to a HO. online synchronization, Centralized data, no need to have Data Centers on all locations. Management and troubleshooting will become easier. very cost effective. It is recommended for Mid-size/large organizations but DRP (Disaster Recovery Plan) should be a necessary part of this network design to prevent form Data and connectivity losses. see below an example of Centralized Network.

Thank you

Best Regards,

S. N. Jafar