Servers are computers that provide services to other computers on a network. Administering servers requires managing, upgrading, and maintaining them to ensure all systems are functioning properly. Network architecture defines communication protocols and hierarchical structures for real-world data exchange between layers. Common network components include nodes, links, and processes. Using standard interfaces makes networks easier to develop, expand, and maintain.

2. Servers are computers that are explicitly set-up to provide services to other computers on the network. Therefore server administration is the task of managing, upgrading and maintaining these servers and making sure that all systems are humming along.

3. We need to know other discipline to administer a server...

4. Network Basics

5. t he logical structure and operating principle of a network system and defines the communication protocols required for real-world data exchange It determines “hierarchical structures” according to each classification and specifies protocols and interfaces between layers of the hierarchical structure.

6. within the network architecture, all the network's physical elements are modeled and structured and treated as a logical network Main components are: node i.e. hardware such as computers and communication equipment link i.e. communication lines process i.e. application programs

7. If the architecture is the same, a system can be built by adjusting the interfaces even when products from different manufacturers are combined Employing a system compliant with standard interfaces makes it easy to develop, expand and maintain the system Even independently developed systems can be easily integrated The entire network can be treated locally

8. Open Network Architecture Vendor-specific proprietary network architecture Open Systems Interconnection Transmission Control Protocol/Internet Protocol Systems Network Architecture (SNA) – IBM DECnet - DEC IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) – Novell Apple Talk – Apple Corporation

9. Network Topology

11. nodes are connected in a closed loop by communication lines transmission lines are short and easily controlled if just one node fails, it might affect the entire network

13. two or more paths lead to each node so that that the overall structure becomes that of a mesh even if a node fails, that node can be bypassed by routing meaning that the reliability of this type of network is high

15. each node is connected to a central node in star shaped configuration even if one node fails, this will have no effect on the overall systems but if the central node fails, the entire network will no longer be functional

17. all nodes are connected to a common communication line makes it easy to add or remove nodes without affecting the overall system and at the same time it is economical when there are many nodes and the traffic load increases data collision may occur on the common communication line and the transmission efficiency may deteriorate

19. several child nodes are connected to a parent node also called cascade connection

20. There are three typical connection methods that are used in accordance with what best suits the communication distance and data load, etc. These are: Point-to-point connection Multipoint connection Switched connection

22. the computer is connected one-to-one to each terminal through a leased line communication lines appropriate if heavy traffic between two points is required

24. multiple branching devices are connected sequentially to the same communication line This configuration allows construction of a network that is cheaper than using the point-to-point configuration when the communication distance is long and the data traffic is light. Since the main communication line is shared, other terminals have to wait while one is transmitting data

26. the lines from several terminals are connected to a concentrator, which is connected to the host computer through a high-speed line

27. No matter what kind of software is running on a network and regardless of what kind of data is transmitted, problem-free data communication will be possible on the OSI complaint network.

28. Application 7 Provides communication services required for applications. i.e. file transfer and management, remote database acces, virtual terminal Presentation 6 Data representation, format translation and mapping Session 5 Performs dialog management. Dialog management controls and manages the data flow between application and systems by emplying the end-to-end data transfer capabilities provided by the transport layer. Transport 4 Guarantees the quality of data transfer between system ends Network 3 Concerned primarily with path selections and relays Data-link 2 Ensures transparent and error-free data transmission by using transmission controls such as high-level data link control, establishment of data-link connection, error control, etc. Physical 1 Transmits electric signals using transmission media