Network Components:
Any network requires hardware components that make up the network so that the nodes within it can communicate with each other and exchange information.
The hardware components used in a local network include the following devices:
Network Interface Cards (NICs)Repeaters
Hubs
Bridges
Switches
Brouters
Routers
Gateways
CSU/DSU.
Wednesday, June 24, 2009
Cellular Topology:
Cellular Topology:
The cellular topology is a wireless topology, where geographic area is divided into cells or regions.
In cellular topology, each cell is a separate entity that is controlled by a central station.
Operates on wireless media, thus do not require cabling.
Easy to install as only requirement is the availability of a central location and signal strength.
The cellular topology is a wireless topology, where geographic area is divided into cells or regions.
In cellular topology, each cell is a separate entity that is controlled by a central station.
Operates on wireless media, thus do not require cabling.
Easy to install as only requirement is the availability of a central location and signal strength.
Mesh Topology:
Mesh Topology:
The mesh topology involves point-to-point connection between every node in the network.
High reliable as network connectivity does not depend on any one node.
Useful for large network connections.
Involves high installation and setup costs due to elaborate cabling required to connect each node with the other node.
Difficult to manage as the size of the network increases.
The mesh topology involves point-to-point connection between every node in the network.
High reliable as network connectivity does not depend on any one node.
Useful for large network connections.
Involves high installation and setup costs due to elaborate cabling required to connect each node with the other node.
Difficult to manage as the size of the network increases.
Ring Topology:
Ring Topology:
The ring topology connects the nodes on a network through a point-to-point connection.
Prevents network collisions by using the token-ring methodEasy to locate cable faults in a ring.
The entire network stops functioning, if any of the nodes in the network
malfunctions.
Expensive devices and cabling.
The ring topology connects the nodes on a network through a point-to-point connection.
Prevents network collisions by using the token-ring methodEasy to locate cable faults in a ring.
The entire network stops functioning, if any of the nodes in the network
malfunctions.
Expensive devices and cabling.
Star Topology:
Star Topology:
The star topology connects nodes over a network using a central control unit called the hub.
Nodes to a star-based network can be easily attached to the hub.
All the nodes are connected to the hub thus requiring lot of cabling and cost.A faulty hub can disrupt the entire network.
The star topology connects nodes over a network using a central control unit called the hub.
Nodes to a star-based network can be easily attached to the hub.
All the nodes are connected to the hub thus requiring lot of cabling and cost.A faulty hub can disrupt the entire network.
Bus Topology:
Bus Topology:
The bus topology connects all the nodes on a network to a main cable called bus.
In the bus topology, each packet that is placed on the bus contains the address of the destination node and is transmitted in both directions along the bus.
A single high capacity cable is required thus requiring minimum cabling and its cost.
Entire cable setup needs to be reconfigured to add a node.
Time consuming process to troubleshoot as every point needs to be checked to locate the fault.
The bus topology connects all the nodes on a network to a main cable called bus.
In the bus topology, each packet that is placed on the bus contains the address of the destination node and is transmitted in both directions along the bus.
A single high capacity cable is required thus requiring minimum cabling and its cost.
Entire cable setup needs to be reconfigured to add a node.
Time consuming process to troubleshoot as every point needs to be checked to locate the fault.
Network Topologies:
Network Topologies:
Network topology is a schematic layout or a map of the arrangement of nodes over a network.
This layout also determines the manner in which information is exchanged within the network.
There are five types of network topologies:
Bus
Star
Ring
Mesh
Cellular.
Network topology is a schematic layout or a map of the arrangement of nodes over a network.
This layout also determines the manner in which information is exchanged within the network.
There are five types of network topologies:
Bus
Star
Ring
Mesh
Cellular.
Introducing Networks:
Introducing Networks:
A network is an interconnection of a group of computers that can communicate and share resources such as hard disks and printers.
The initial idea of a network was perceived by Department of Defense (DOD) in USA for the purpose of security.
Some advantages of networks are:
Sharing of information across the network
Optimum utilization of hardware resources
Centralization of data management.
A network is an interconnection of a group of computers that can communicate and share resources such as hard disks and printers.
The initial idea of a network was perceived by Department of Defense (DOD) in USA for the purpose of security.
Some advantages of networks are:
Sharing of information across the network
Optimum utilization of hardware resources
Centralization of data management.
Mirrored Servers:
Mirrored Servers:
Similar to redundant disk drives, mirrored servers provide the fault-tolerance and redundancy that mission-critical information systems need.
A mirror server stores a copy of data contained on multiple servers. Instead of connecting to the primary site, clients connect to the mirror server and obtain files from it.
Using mirrored servers has a few drawbacks as listed below:
Files are mirrored on the server only at periodic intervals.
Several files on the mirrored server may not be ever accessed.
The mirror server can only store a limited number of files on the Internet.
Similar to redundant disk drives, mirrored servers provide the fault-tolerance and redundancy that mission-critical information systems need.
A mirror server stores a copy of data contained on multiple servers. Instead of connecting to the primary site, clients connect to the mirror server and obtain files from it.
Using mirrored servers has a few drawbacks as listed below:
Files are mirrored on the server only at periodic intervals.
Several files on the mirrored server may not be ever accessed.
The mirror server can only store a limited number of files on the Internet.
Transaction Servers:
Transaction Servers:
A transaction server manages applications and database transaction requests on behalf of client computers.
The basic purpose of using a transaction server is to make available the same business transaction to multiple users across the Internet, which enables a greater reach to customers and business partners.
A transaction server manages applications and database transaction requests on behalf of client computers.
The basic purpose of using a transaction server is to make available the same business transaction to multiple users across the Internet, which enables a greater reach to customers and business partners.
Catalog Servers:
Catalog Servers:
Catalog servers are used for user authentication.
If the number of users logging onto a network is high, then it is important to have an adequate number of global catalog servers at the site to handle the high volume of authentication requests and a quick connection to handle each request efficiently.
However, too many catalog servers can slow down the network by creating unnecessary replication traffic.
Catalog servers are used for user authentication.
If the number of users logging onto a network is high, then it is important to have an adequate number of global catalog servers at the site to handle the high volume of authentication requests and a quick connection to handle each request efficiently.
However, too many catalog servers can slow down the network by creating unnecessary replication traffic.
Certificate Servers:
Certificate Servers:
Certificates are digitally signed documents that enable you to use smart card logon, send encrypted e-mail, and sign electronic documents.
Certificates contain a public key and a set of algorithms for encryption, decryption, and authentication. A repository of these certificates is known as a certificate server.
Windows 2000 Server supports Certificate Services, which can be used to issue certificates.
Certificates are digitally signed documents that enable you to use smart card logon, send encrypted e-mail, and sign electronic documents.
Certificates contain a public key and a set of algorithms for encryption, decryption, and authentication. A repository of these certificates is known as a certificate server.
Windows 2000 Server supports Certificate Services, which can be used to issue certificates.
Proxy and Caching Servers:
Proxy and Caching Servers:
Proxy servers act as an intermediary link between the client and the server.
Their purpose is to hide the server from the client without disturbing the communication link between the two.
When a client sends a request for a Web page, the request is routed to the proxy server. It first looks for the Web page in its memory.
If the Web page exists, it sends back that page to the client.
If the requested page does not exist in the cache server’s memory, it fetches the requested page from the server that is hosting it on the Internet and then maintains a copy of that Web page.
All successive requests for this page or file is fetched from the cache of the server.
Proxy servers act as an intermediary link between the client and the server.
Their purpose is to hide the server from the client without disturbing the communication link between the two.
When a client sends a request for a Web page, the request is routed to the proxy server. It first looks for the Web page in its memory.
If the Web page exists, it sends back that page to the client.
If the requested page does not exist in the cache server’s memory, it fetches the requested page from the server that is hosting it on the Internet and then maintains a copy of that Web page.
All successive requests for this page or file is fetched from the cache of the server.
News Servers:
News Servers:
A news server stores, organizes, and distributes the messages posted in
newsgroups.
A newsgroup is a discussion on a specific topic in the form of notes over Internet sites distributed over Internet sites using the news server.
The working of a news server consists of the following steps:
When a user needs to share a message with other users, the message is posted on the news server.
The news server transmits the message to other news servers over the Internet.
When other users reply to the shared message, the reply is sent back to the news server on which the message was posted.
A news server stores, organizes, and distributes the messages posted in
newsgroups.
A newsgroup is a discussion on a specific topic in the form of notes over Internet sites distributed over Internet sites using the news server.
The working of a news server consists of the following steps:
When a user needs to share a message with other users, the message is posted on the news server.
The news server transmits the message to other news servers over the Internet.
When other users reply to the shared message, the reply is sent back to the news server on which the message was posted.
Domain Name Servers:
Domain Name Servers:
DNS is a service used on the Internet to translate Fully Qualified Domain Names (FQDN) to their actual Internet Protocol (IP) addresses.
DNS is the de facto naming system for IP–based networks and the naming service that locates computers on the Internet.
DNS is a distributed database that provides a hierarchical naming system for identifying hosts on the Internet.
Name resolution is the process by which DNS resolves the domain names to IP addresses.
The name resolution process done is as follows:
A client sends a query to its local name sever.
In case the local server is unable to resolve the request, it passes on the query to other name servers on behalf of the client.
DNS is a service used on the Internet to translate Fully Qualified Domain Names (FQDN) to their actual Internet Protocol (IP) addresses.
DNS is the de facto naming system for IP–based networks and the naming service that locates computers on the Internet.
DNS is a distributed database that provides a hierarchical naming system for identifying hosts on the Internet.
Name resolution is the process by which DNS resolves the domain names to IP addresses.
The name resolution process done is as follows:
A client sends a query to its local name sever.
In case the local server is unable to resolve the request, it passes on the query to other name servers on behalf of the client.
Other Internetworking Servers:
Other Internetworking Servers:
Some of the internetworking servers are:Domain Name Servers (DNS) News servers Proxy and caching servers.
Certificate servers.
Catalog servers.
Transaction servers.
Mirrored servers.
Some of the internetworking servers are:Domain Name Servers (DNS) News servers Proxy and caching servers.
Certificate servers.
Catalog servers.
Transaction servers.
Mirrored servers.
Working with File and Print Services:
Working with File and Print Services:
The File and Print services in an organization enable users to have quick,
guaranteed, and secure access to their data.
In Windows 2000 operating system, file and print services are enabled, by default.
The File and Print services in an organization enable users to have quick,
guaranteed, and secure access to their data.
In Windows 2000 operating system, file and print services are enabled, by default.
Internetworking:
Internetworking:
Internetworking services are the services in a networking environment that are accessible to users within an intranet or the Internet.
The following are some of the services provided by the Internetworking servers:
File Transfer
WWW
E-mail.
Telnet.
Usenet newsgroups.
Internetworking services are the services in a networking environment that are accessible to users within an intranet or the Internet.
The following are some of the services provided by the Internetworking servers:
File Transfer
WWW
E-mail.
Telnet.
Usenet newsgroups.
LINUX:
LINUX:
The Linux network operating system, developed by Linus Torvalds, is based on the UNIX architecture.
Linux is an open source operating system in which the source code or the program of the operating system is available free of cost.
This provides flexibility to the user to modify the operating system according to individual requirements.
Linux provides services like Apache, Samba and NFS.
The Linux network operating system, developed by Linus Torvalds, is based on the UNIX architecture.
Linux is an open source operating system in which the source code or the program of the operating system is available free of cost.
This provides flexibility to the user to modify the operating system according to individual requirements.
Linux provides services like Apache, Samba and NFS.
UNIX:
UNIX:
Bell Labs launched the UNIX network operating system.
Many versions of UNIX, such as Sun Solaris, AIX UNIX, HP UNIX, and BSD, are available in the market.
Some of the features of UNIX, which allow networking at the operating system level, are:Internet-based services Compatibility with different protocols Network security.
Bell Labs launched the UNIX network operating system.
Many versions of UNIX, such as Sun Solaris, AIX UNIX, HP UNIX, and BSD, are available in the market.
Some of the features of UNIX, which allow networking at the operating system level, are:Internet-based services Compatibility with different protocols Network security.
Novell Netware:
Novell Netware:
Novell Netware is a product of Novell, Inc.
The Novell Netware operating system architecture is also based on the client-server model. Netware provides various server versions for managing networks.
Some of the features of Netware 6.x are:
Novell Directory Services (NDS).
TCP/IP encapsulation.
Clustering and multiprocessor support.
Novell Netware is a product of Novell, Inc.
The Novell Netware operating system architecture is also based on the client-server model. Netware provides various server versions for managing networks.
Some of the features of Netware 6.x are:
Novell Directory Services (NDS).
TCP/IP encapsulation.
Clustering and multiprocessor support.
Windows NT/2000:
Windows NT/2000:
Windows NT is a 32-bit operating system. It is a Microsoft product, which operates on single and multiprocessor systems.
Windows 2000 is another network operating system developed by Microsoft and is based on Windows NT technology.
The features of the Windows 2000 operating system are as follows:
Active Directory Virtual Private Networks (VPNs):
Terminal server Symmetric multiple processing.
NTFS 5.0
Remote installation services.
Windows NT is a 32-bit operating system. It is a Microsoft product, which operates on single and multiprocessor systems.
Windows 2000 is another network operating system developed by Microsoft and is based on Windows NT technology.
The features of the Windows 2000 operating system are as follows:
Active Directory Virtual Private Networks (VPNs):
Terminal server Symmetric multiple processing.
NTFS 5.0
Remote installation services.
Network Operating System:
Network Operating System:
Network Operating System (NOS) is an enhanced version of an operating system, with features that allow the management and connectivity of nodes within a network.
NOS allows the sharing of information and resources based on the accessibility privileges allocated to each user or node.Popular NOSs include:
Windows NT/2000.
Novell Netware.
UNIX.
Linux.
Network Operating System (NOS) is an enhanced version of an operating system, with features that allow the management and connectivity of nodes within a network.
NOS allows the sharing of information and resources based on the accessibility privileges allocated to each user or node.Popular NOSs include:
Windows NT/2000.
Novell Netware.
UNIX.
Linux.
File Systems:
File Systems:
A file system is an entire framework used by an operating system to name, organize, and store files.
Windows Server 2003 supports the following file systems:
FAT.
FAT 32.
NTFSDFS.
A file system is an entire framework used by an operating system to name, organize, and store files.
Windows Server 2003 supports the following file systems:
FAT.
FAT 32.
NTFSDFS.
Functions of Operating System:
Functions of Operating System:
The various tasks that an operating system performs are:
Process Management.
I/O Operations .
File Management .
Memory Management.
The various tasks that an operating system performs are:
Process Management.
I/O Operations .
File Management .
Memory Management.
What is an Operating System:
What is an Operating System:
A computer uses its software to store, process and retrieve information.A computer software can be divided into two types.
1.Application software .
2.System software .
Application software enables users to perform specific task.
System software enables a computer to function. The operating system provides a consistent environment for other software to execute commands.
The operating system becomes the center through which the system hardware, other softwares, and the user communicate.
A computer uses its software to store, process and retrieve information.A computer software can be divided into two types.
1.Application software .
2.System software .
Application software enables users to perform specific task.
System software enables a computer to function. The operating system provides a consistent environment for other software to execute commands.
The operating system becomes the center through which the system hardware, other softwares, and the user communicate.
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