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Network Servers
Chapter 13
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
DHCP Server Responsibilities Address Storage and Management Configuration Parameter Storage and Management Lease Management Responding To Client Requests Providing Administration Services
Release 16/7/2009
DHCP Client Responsibilities
Configuration Initiation Configuration Parameter Management Lease Management Message Retransmission
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009
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
Release 16/7/2009