Network Servers

Chapter 13

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Chapter Objectives

Describe Client-server and Peer to Peer network model

Explain E-mail server Explain Domain Name System Explain Dynamic Host Configuration Protocol Describe Windows Internet Name Service State the features of Network Operating System

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Recall

Types of wireless network: Peer-to-Peer (P2P) or Ad-Hoc Access Point or Infrastructure wireless LAN

802.11 is a standard created by Institute of Electrical and Electronic Engineers (IEEE) for defining all aspects of Radio Frequency Wireless networking

Applications are Wireless Local Area Network (WLAN), Wireless Wide Area Network (WWAN), Wireless Personal Area Network (WPAN) and Mobile Computing

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Client-Server and Peer to Peer - I Client – Server

Consist of one or more clients and only one server

It is not possible for one client to access shared resources on another client system

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Client-Server and Peer to Peer - II Peer to Peer

Computers on the network can have access to resources and data. The computers act as both clients and servers

Computers are able to communicate with each other and share data with other users

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Types of Servers Servers are classified depending on the nature of

work Types:

File Server Print Server Mail Server Database Server FTP Server DNS Server DHCP Server WINS Server

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Sharing Resources on Network Networking tasks includes sharing files and network

recourses and setting up network security User can share:

Internet connection among multiple computers Several numbers of files, folders to avoid data

redundancy over Local Area Network

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E-Mail Server

Often referred as mail server Receives and delivers e-mails over the network Maintains a storage area for e-mails Employs a set of user defined rules that determine

the strategy for mail server to respond according to the destination of a specific message

Most e-mail servers use Linux OS as they less prone to viruses

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Domain Name System (DNS)

Two ways to resolve names: NetBIOS and DNS Technique used to provide standard naming

conventions for finding IP address configured hosts Uses hierarchical name space and distributed

database Internet domains are classified into various

categories like “root” or the top most level of the Internet domain namespace

DNS is based on logical tree structure called domain name space

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DNS Namespace Categories of top-level domains:

Organizational domain – e.g. .com Geographical domain – e.g. .uk Reverse domain – in-addr.arpa

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DNS Server - I Contains information about the zones Zones are continuous portion of the domain name

system namespace

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DNS Server - II

A complete DNS name including the host name and all of its domains is known as fully qualified domain name (FQDN)

A single DNS server contain all the host names on the domain and their corresponding IP address in the entire network is known as authoritative DNS server

No two machines should have the same FQDN

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Name Resolution In DNS

Name can be resolved in three ways: by consulting locally stored text file called HOSTS, by contacting a DNS server or by broadcasting

As the database is centralized on the DNS server, it is easy for the administrator to add new entries just once rather than adding new entries to each machines

DNS server has to know about other DNS servers where it can go for more information

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Dynamic Host Configuration Protocol(DHCP) Provides dynamic configuration of IP addresses on

time lease basis Provides information like IP address, default

gateway, DNS address and so on Backward compatible with BOOTP DHCP Server employs manual, automatic and

dynamic IP address allocation methods Reduces administration of a TCP/IP network

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DHCP Server Responsibilities Address Storage and Management Configuration Parameter Storage and Management Lease Management Responding To Client Requests Providing Administration Services

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DHCP Client Responsibilities

Configuration Initiation Configuration Parameter Management Lease Management Message Retransmission

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IP Address Allocation

DHCP provides temporary IP address with a particular amount of time

Methods of allocating IP address to the hosts: Manual allocation – IP addresses are manually

entered by server administrator Automatic allocation – Assigns the requesting client

an IP address from a pool of IP address Dynamic allocation – Makes use of IP address

request and permits process with time lease

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WINS - I

Windows Internet Name Service Maps Network Basic Input/Output System

(NetBIOS) computer names to corresponding IP addresses

Was created to resolve the problems of broadcast-based name resolution

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WINS - II

WINS Client Name Registration In WINS database NetBIOS, the WINS-enabled

client registers the names of processes running on it.

These client names should be renewed in the WINS database

WINS Client Name Renewal The renewal interval determines how long the server

stores the name registration as an active record in the WINS database

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WINS – III

WINS Client Name Release NetBIOS names are released explicitly or silently

WINS Client Name Resolution WINS server accepts client’s name resolution request A system name and a share name needs to be

specified by the user in order to connect to a network drive

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WINS - IV

WINS Client Behaviour Basic functions that a WINS client includes;

Startup Plugging to subnet Extended shutdowns Establishing connections

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Show how to configure WINS

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Troubleshooting WINS

Most WINS problems are not directly related to WINS rather they are related to NetBIOS

Nbtstat is used to troubleshoot NetBIOS name resolution problems

NetBIOS over TCP/IP (NetBT) resolves NetBIOS names to IP addresses

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NOS - I Network Operating System An Operating System for computer that can be

connected in network Organizes the activities of multiple computers

across a network Windows NT (New Technology)

Contains advanced features for security, network support, multitasking and user administration

Basically two products; Windows NT Workstation and Windows NT Server

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NOS - II Windows 2000

Improved version of Windows NT No need to configure or use NetBIOS Desktop and a server version of Windows 2000:

Windows 2000 Professional Windows 2000 Server

Active directory - Centralized storage area of information about network resources related to users, applications, files and printers

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NOS - III Windows 2003 Server

.NET version of the Windows 2000 server operating system

Windows Server 2003 editions: Small Business Server (Standard and Premium Edition) Web Edition Standard Edition Enterprise Edition Datacenter Edition

Windows XP Professional Device support, user friendly and Remote Desktop Multiple users can log in and use the system without

logging out the previous users

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NOS - IV

Novell Netware Novell Corporation is a local-area network (LAN)

operating system Netware supported different types of LAN

technologies from Ethernet to IBM’s token-ring networks

Linux An open source computer operating system Linux is based on UNIX operating system which was

designed to support networking

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Summary - I

In Client-Server model, server controls the network In P2P network, all the PCs act as both clients and

servers A Mail server is an application that receives e-mail from

local net users, remote users and delivers these e-mails to the intended users

Name resolution is the process of mapping computer names to their associated IP addresses and this service is provided by DNS

Domain Name System (DNS) maps Fully Qualified Domain Name (FQDN) to corresponding IP address

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Summary - II

DHCP protocol is an extension to the Bootstrap Protocol (BOOTP) and used by the clients on the network to obtain IP address automatically

DHCP provides temporary IP address with a particular amount of lease time

Windows Internet Name Service maps Network Basic Input/Output System (NetBIOS) computer names to corresponding IP addresses

A network operating system (NOS) deals concurrent requests from clients and provides the security necessary in a multi-user environment

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