1. Network Services

2. Peer-to-Peer Networks
Workstations share files or printers among themselves.
Best suited to smaller networks (<= 10 users)‏
Advantages include
low cost,
ease of installation and
users directly manage resource sharing.
Main disadvantages
Lack of central control
possibilities of security weaknesses due to mismanagement of sharable resources.

3. Client-Server Architecture
Computer servers provide services
File storage, databases, printing services, login services, web services
Client computers
Execute programs in its own memory
Access files either locally or can request files from a server

4. Client / server architecture
Major benefit is centralisation.
Server provides a central control point for network provision, security and management.
Disadvantages include
higher cost of dedicated servers
large amount of administration effort.

5. Directory Services
Used to manage users & devices on larger (client server) networks
Consists of
Domain control
Account management
Users
Groups
Authentication management

6. Domains
2 main types
Internet domains
Organisation domains

7. Internet domain names
IP addresses are 32 bit binary e.g is “human friendly” version of
Humans prefer words
=>Domain names e.g. llandrillo.ac.uk
Early ARPAnet used a central list called hosts.txt to map names to numbers
Changes ed out!

8. Domain names
Now distributed database called Domain Name System (DNS) used
“Root” is administered by Internet Assigned Numbers Authority (IANA)‏
“Root” consists of several networks but logically is a single point
Top Level Domains (TLDs) are next level down from “Root”
TLDs may be country based (e.g. uk, jp) or generic (e.g. com, org)‏

9. Domain names Each TLD has a sponsoring organisation responsible for
allocating domain names within their TLD
running master name servers for their TLD
UK’s is Nominet UK (
Most domain name registration delegated to “registration agents”
Cheaper to register small numbers of domain names through an agent
Domain details through whois query

10. Whois query for cadburys.co.uk

11. Domain name resolution
If a host doesn’t know the address for a domain name it will send a query to a defined DNS server
DNS server normally run by the ISP
If DNS server doesn’t know the address it will send a query to a higher level DNS server.
Process is repeated until the address is found.

13. Organisation domains Often refers to Windows based network
Logical group of computers which share a central directory database
Each user has a single unique username for use across the domain
One major difference between Home & Pro versions of Windows XP was ability to join a domain.

14. Windows domains Servers e.g. Clients e.g. Windows Server 2003
Windows XP Pro
Windows Vista

15. Account Management User account contain info like... User name
Password
Password expiry date
Personal details e.g. real name
address
Groups you are member of
File / directory access rights
Server /printer access rights
Web access rights / restrictions

16. User groups
User rights / restrictions are rarely assigned to individuals
Too time consuming
Complex
Possibility of error
Rights / restrictions assigned to groups
Users made members of groups
Users inherit group rights / restrictions

17. Authentication Occurs in many different ways User authentication
normally by username & password
Account may be locked if wrong password attempted too many times

18. Other types of authentication
Internet ecommerce & secure webpages
Secure Wide Area Network connections
Routers, servers etc
Wireless systems WEP, WPA etc.