Network Servers Chapter 13 Release 16/7/2009

Chapter Objectives Describe Client-server and Peer to Peer network model Explain 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 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 Release 16/7/2009

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 Release 16/7/2009

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 Release 16/7/2009

Server Often referred as mail server Receives and delivers s over the network Maintains a storage area for s 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 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 Release 16/7/2009

DNS Server - I Contains information about the zones Zones are continuous portion of the domain name system namespace Release 16/7/2009

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 Release 16/7/2009

WINS - IV WINS Client Behaviour  Basic functions that a WINS client includes; Startup Plugging to subnet Extended shutdowns Establishing connections Release 16/7/2009

Show how to configure WINS Release 16/7/2009

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 from local net users, remote users and delivers these s 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