INTRODUCTION TO NETWORKING

INTRODUCTION

A network is simply a group of two or more Personal Computers linked together. Many types of networks exist, but the most common types of networks are Local-Area Networks (LANs), and Wide-Area Networks (WANs).

In a LAN, computers are connected together within a "local" area (for example, an office or home). In a WAN, computers are further apart and are connected via telephone/communication lines, radio waves or other means of connection.

HOW ARE NETWORKS CATEGORIZED?

Networks are usually classified using three properties: Topology, Protocol and Architecture.

Topology specifies the geometric arrangement of the network. Common typologies are a bus, ring and star.You can check out a figure showing the three common types of network typologies here.

Protocol specifies a common set of rules and signals the computers on the network use to communicate. Most networks use Ethernet, but some networks may use IBM's Token Ring protocol. We recommend Ethernet for both home and office networking. For more information, please select the Ethernet link on the left.

Architecture refers to one of the two major types of network architecture: Peer-to-peer or client/server. In a Peer-to-Peer networking configuration, there is no server, and computers simply connect with each other in a workgroup to share files, printers and Internet access.

This is most commonly found in home configurations and is only practical for work groups of a dozen or less computers. In a client/server network there is usually an NT Domain Controller, to which all of the computers log on. This server can provide various services, including centrally routed Internet Access, mail (including e-mail), file sharing and printer access, as well as ensuring security across the network. This is most commonly found in corporate configurations, where network security is essential.

DOMAIN NAME SYSTEM (DNS)

DNS is a very popular and well known protocol. It is used for resolving host names and domain names to IP addresses. The fact is that when you type www.tecsavvy.com the name is translated into an IP address via a number of queries that take place from your PC towards the DNS server. This DNS Query process (and more) is analysed in great depth in the articles that follow.

The amount of information covering the DNS protocol has been broken into smaller sections to help avoid confusion and make the learning process as easy as possible.

Following is a break-down of the articles provided and information they contain:

Section 1: The DNS Protocol. How and why the DNS protocol was born. Page contains a bit of historical information and also compares DNS with the OSI Reference model, where you will see the layers on which DNS works. Internet DNS hierarchy is also analysed here, giving you the chance to understand how domains on the Internet are structured.

Section 2: The DNS Resolution Process. What really happens when a host requests a DNS resolution. Full analysis of the whole resolution process using a real life example. Understand Name Servers and the role they play in the DNS system.

Section 3: The DNS Query Message Format. This section, along with the next one gives you the DNS packet format in all its glory. Learn how DNS queries are generated and formatted. See, learn and understand the various fields within the packets as your taken through a full detailed analysis of the packet structure using the cool 3D diagrams.

Section 4: The DNS Response Message Format. This is the continuation of the section above, dealing with the DNS response that's received. You will learn how the response packet is generated, formatted and sent to the resolver. Again, you're taken through a full detailed analysis of the packet structure using the cool 3D diagrams.

The OSI Model network fundamental

OSI is a standard description or "reference model" for how messages should be transmitted between any two points in a telecommunication network. Its purpose is to guide product implements so that their products will consistently work with other products.

The Model 

The OSI model was created by the IEEE committee so different vendors products would work with each other. You see the problem was that when HP decided to create a network product, it would be incompatible with similar products of a different vendor e.g IBM.

So when purchasing 40 network cards for your company, you would need to make sure that the rest of the equipment would be from the same vendor, to ensure compatibility.  It is  quite clear that things were very restrictive, until the OSI model came into the picture.

As most are aware of, the OSI model consists of 7 layers.

Each layer has been designed to do a specific task. Starting from the top layer (7) we will see how the data which you type gets converted into segments, the segments into datagrams and the datagrams into packets, the packets into frames and then the frames are sent down the wire, usually twisted pair, to the receiving computer.

Full in-depth analysis of each layer is available using the links to the articles at the bottom of this page.

 The diagram below is a quick summary of the OSI Layers and their functions:

How to access a Certain Drive using Command prompt (CMD)

Now you are working on the 'C:' drive. If you need to go to a specific folder from this drive just type CD DIRECTORYNAME. The subdirectory names are separated by \. For example when you need to access the System32 folder that is located on 'C:\Windows' just type cd windows\system32\, as shown below, and then press Enter.

When you need to go to one folder up, use the cd.. command. Let's assume that you want to go back to the Windows folder. Type cd.. and press Enter. You will notice that your current directory has changed to 'C:\Windows'.

How to Access a Certain Drive

To access another drive just type the drive letter followed by ':'. For example, we wanted to change the drive from 'C:' to 'D:'. We have typed d: and then pressed Enter.

To change the drive and the directory at the same time, use the cd command followed by the/d switch. The parameter is used to change the current drive to a specific folder from other partition. For example, now you are on the 'D:' drive and you want to go back to the 'C:'drive directly to the Windows folder. Type cd/d C:\Windows and press Enter, as you can see in the following image.

Note: By typing the drive letter you automatically move to your most recent location in that drive. For example if you are on 'd:' drive and type cd c:\windows nothing happen. But, if you type 'c:' then the working will change to c:\windows (assuming that it was the last directory you worked with on c: drive).

How to View the Content of a Folder

You can view the content of a folder by using a simple command called DIR. To test, we've created on the 'd:' drive a folder named 7tutorials with several files and subfolders.

For more information please check the below links :

http://www.7tutorials.com/command-prompt-how-use-basic-commands

Preparing computers for use with Simplified Disaster Recovery

Description

Prepare computers for use with Simplified Disaster Recovery (SDR) by performing the following steps:

Table: Preparing computers for use with Simplified Disaster Recovery

Step	Description	More information
Step 1	Specify an alternate location where copies of the disaster recovery information files are stored.	Backup Exec creates the disaster recovery information file after a backup job that includes all critical system components completes successfully. Backup Exec then stores the disaster recovery information file in the default storage location with the backup set on a disk storage or disk cartridge device, and in the alternate storage locations. Catalog entries from subsequent backups are automatically added to the disaster recovery information file. Warning: If you back up a computer to a tape device, deduplication storage, or a virtual disk, Backup Exec cannot store a disaster recovery information file with the backup set. You must have a disaster recovery information file in an alternate location to ensure that you can use SDR to recover the computer. See Setting or changing the alternate location for the disaster recovery information file.
Step 2	Run the backup jobs that include all critical system components (SDR-enabled backups) for the computers that you want to protect. These are the backups for which the Simplified Disaster Recovery indicator is ON. Note: For environments running the Central Admin Server Option, run a database maintenance job before you run SDR-enabled backups. Otherwise, the central administration server denies communication attempts from the managed Backup Exec servers. See Configuring database maintenance and security.	By default, Backup Exec selects all critical system components when you select a computer for backup. When all critical system components are included in the backup job selections, the Simplified Disaster Recovery indicator on the backup selections appears as ON. If you deselect one or more critical system component files, the indicator appears as OFF. Symantec recommends that you select the entire computer for backup; otherwise, Backup Exec cannot create the system-specific disaster recovery information file. Critical system components include the following: System volume (including EFI and utility partitions) Boot volume (executing operating system) Services application volumes (boot, system, and automatic startup) System State devices and volumes (including Active Directory, system files, and so on) See How to ensure that backups are enabled for Simplified Disaster Recovery.
Step 3	Create additional copies of the disaster recovery information files and store them in a safe place.	Backup Exec stores the important disaster recovery information files in the default path, the alternate location, and with the backup set if disk storage or disk cartridge devices are used as the destination storage. Symantec recommends that you also make additional copies of the files and store them in a safe place. Without the disaster recovery information files, you cannot recover Backup Exec servers by using Simplified Disaster Recovery (SDR). Having multiple copies of the disaster recovery information files ensures that you can successfully recover Backup Exec servers with SDR. By default, the disaster recovery information files reside in the\Program Files\Symantec\Backup Exec\SDR\Datadirectory on the Backup Exec server. Use Windows Explorer or another Copy utility to copy the disaster recovery information files from the default location to another storage location of your choice. Backup Exec does not automatically update these copies, but they do let you restore a computer to an older point-in-time if the other disaster recovery files are not available
Step 4	Use the Create Simplified Disaster Recovery Disk Wizard to create a disk image, and then a bootable CD or DVD recovery disk.	Backup Exec generates alerts after each backup job until you create the Simplified Disaster Recovery disk image. You can disable these alerts, but Symantec recommends that you create the Simplified Disaster Recovery disk image. See Creating a Simplified Disaster Recovery disk image. If you install the Create Simplified Disaster Recovery Wizard on a standalone server, you cannot use the wizard to run LiveUpdate. For instructions on how to manually run LiveUpdate, go to the following URL: http://www.symantec.com/docs/TECH136135

References :

 http://www.symantec.com/docs/HOWTO99605

Authoritative Restore using Backup Exec

Authoritative Restoration :

An authoritative restore is most commonly used in cases in which a change was made within the directory that must be reversed, such as deleting an organization unit by mistake. This process restores the DC from the backup and then replicates to and overwrites all other domain controllers in the network to match the restored DC. The especially valuable thing about this is that you can choose to only make certain objects within the directory authoritative. For example, if you delete an OU by mistake you can choose to make it authoritative. This will replicate the deleted OU back to all of the other DC’s in the network and then use all of the other information from these other DC’s to update the newly restored server back up to date. 

1. 
   
2. 1) At the remote server, press F8 during startup.
   A menu appears that allows you to diagnose and fix system startup problems.
3. Select Directory Services Restore Mode.
4. 
   
5. At the media server, start Backup Exec.
6. From the navigation bar, click Restore.
7. 
   
8. Select System State (Windows 2000 and later) or Shadow Copy (Windows 2003 and later) components as the restore selections.
9. From the Properties pane, under Source, select Resource Credentials.
10. Highlight the restore selection for the remote server and click New.
11. Create a new logon account for this restore job. The account should have administrator privileges on the remote server.
12. Select the new logon account and click OK.
13. Run the Restore job.
    At the remote server:
14. At this point, you can either choose to restore the entire Active Directory, or specific objects from the Active Directory:
    Restore the entire Active Directory by performing the following:

    • Open a command prompt.
    • Type NTDSUTIL and press Enter.
    • Type Authoritative Restore and press Enter.
    • Type Restore Database, press Enter, click OK and then click Yes.
    See Microsoft's documentation for running NTDSUTIL on Windows Server 2008/2008 R2.
    Restore specific objects from the Active Directory by performing the following:

    • Open a command prompt.
    • Type NTDSUTIL and press Enter.
    • Type Authoritative Restore and press Enter.
    • Type Restore Subtree "ou=<OU Name>.dc=<domain name>,dc=<xxx> (without the quotation marks), and then press Enter, where <OU Name> is the name of the organizational unit you want to restore, <domain name> is the domain name the OU resides in, and <xxx> is the top level domain name of the domain controller, such as com, org, or net. You can do this as many times for as many objects you need to restore.
15. Once you have finished restoring Active Directory information, exit NTDSUTIL.
16. Restart the computer.

For more information please follow the below Tech notes

https://support.symantec.com/en_US/article.HOWTO23130.html

Non-Authoritative Active Directory Disaster Recovery scenario

I navigated over the topics here, and I could see that we have a lot of posts regarding Active Directory/Domain Controller, but almost all the time related to Backup Exec.

My current scenario is:

- We prepared a Virtual Environment out of our productive network;

- We installed a Master/Media Server there, and we intend to restore from productive network, all tapes where Active Directory/Domain Controller was backed up, to Test environment;

- We have AD/DC installed on Windows 2003 and 2008;

 

When I read suggested documentation, I couldn't make sure what to do for complete recovery for AD/DC.

 

My idea is, Install OS is all machines that we intend to recover, and so, restore System State/Shadow Copy Components.

 

Some of you already tested the following documentation?

 

https://www-secure.symantec.com/connect/forums/backuprestore-domain-controller

 

The main doubt that I have is on step 5:

 

5. Perform a full system restore.

 What it means? Restore everything together (C:, System State/Shadow Copy Components)? Or I have to restore one by one, restart, etc

 for more information please follow the given below article

https://support.symantec.com/en_US/article.TECH56473.html 

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