Network Engineer

1. BCS Level 4 Certificate in Network Systems and Architecture Features of Client-Server Operating Systems and Applications Network Engineer

2. 9 Features of Client-Server Operating Systems and Applications (10%) 9.1 Describe the typical client operating system features. • designed for end user; • includes a GUI; • accesses resources provided by a server; • user applications are locally installed. 9.2 Explain the typical server operating system features. • shares resources to client systems; • stores resources centrally for easy management • may have a GUI and / or CLI.

3. 9 Features of Client-Server Operating Systems and Applications (10%) 9.3 Describe the function of different types of server. • Directory Active Directory / NIS • DNS • web proxy server; • file and print; • email; • database; • virtualisation.

4. 9 Features of Client-Server Operating Systems and Applications (10%) 9.4 Explain the key function of business application software. • sales - customer relationship management; • marketing - presentation and communication; • finance - accountancy packages; • HR - employee record management; • Technical support – helpdesk; • general – communication; • email; • instant chat; • VOIP; • video conference.

5. Client operating system features • A client is a computer that requests services from a server via a network • The server may be located locally or remotely • Typical desktop client OS are: • Windows • Linux distributions (eg Mint, Ubuntu) • OSX • Chrome • Typical mobile client OS are: • Android • iOS

6. Client operating system features • Required features: • Networking (TCP/IP stack) • Wired and wireless network support • Graphical user interface (GUI) • Local application support (eg for browser) • Optional features: • Local storage • Local processing

7. Fat/thick client • Performs most of the processing • Large set of features • Supports powerful local applications • Significant local storage • Little reliance on a server • Complex to manage • Known as a workstation if only uses a file server • Examples: • Windows • Linux • OSX

8. Thin client • Most processing done on a server • Small set of features • No local applications • Total reliance on a server • Managed from the server • Examples: • Citrix • Windows Embedded

9. Hybrid client • Processes locally • Persistent data stored on a server • Small set of features • Restricted local storage • Simple to manage • Examples: • Chrome OS

10. Server operating system features • Ability to access the server both in GUI and command-level interface • Stores resources centrally for easy management • Execute all or most processes from OS commands • Advanced-level hardware, software and network configuration services • Install/deploy business applications and/or web applications • Provides central interface to manage users, implement security and other administrative processes • Manages and monitors client computers and/or operating systems • Common examples of server OS include: • Linux Server • Windows Server  .

11. Managing server operating systems • Can be configured with CLI only (reduced footprint) • Servers can be headless • No keyboard, mouse or monitor • Managed with • Remote desktop • PuTTY • Browser (eg for ESXi) • Accessed via KVM • Normal keyboard, mouse and monitor

12. Active Directory (AD) – Windows server • A server running Active Directory Domain Services is called a domain controller • A domain is a network in which all user accounts, computers and printers are registered with a central database located on one or more domain controllers.  • AD services: • Authenticate, define access rights and authorise all users and computers in the domain • Used by • Group Policy • Encrypting File System • BitLocker • Domain Name Services • Remote Desktop Services • Exchange Server • SharePoint Server

13. NIS – network information service • A Linux/Unix central directory of: • user and group information • hostnames • e-mail aliases • other text-based tables of information • Authenticates users • Similar to Windows active directory (but pre-dates it)

14. Domain Names • Matches domain names (internet sites) to IP addresses • Domains are organised in a tree structure • The root of the tree is . (dot) • Beneath the root are the top level domains (.com, .uk etc) • Beneath the top level domains (TLDs) are second level domains (.microsoft, .ac, .gmail etc) • Below those are further sub domains (eg .gloscol)

15. Domain Name System • The system consists of Domain Name Servers which provide the domain name to IP address mapping • There are 13 root servers on the internet • There are then many TLD name servers (1,000 in 2015) • There are a multitude of sub domain servers

16. Iterative name resolution

17. Name resolution • The client which issues the query is called a resolver • In order to speed up the process caching is used • At name servers • In the resolver • Cached records have a limited time to live (TTL) • This means that caches are updated as new or altered records are added to the name servers • View the DNS resolver cache in W10 using the command:ipconfig /displaydns

18. DNS record format

19. DNS record types Canonical means “according to the rules” A CNAME record links an alias name to another true or canonical domain name. For instance, www.example.com might link to example.com.

20. Web proxy server • Gives access to content on the World Wide Web, providing anonymity • May be used to bypass IP address blocking • Firewall may block unauthorised IP addresses • Client requests such an address via the proxy • Proxy is not blocked by the firewall • Improve performance • A company can send all page requests via a proxy • The proxy caches the results • Subsequent requests for that page are served from the cache

21. Reverse proxy server • Reverse proxy server receives all incoming requests • Directs requests to correct server • Used for: • Load balancing • DDOS protection • Caching • SSL encrytpion

22. Print server • Connects clients (desktops etc) to printers • Printers can be networked or directly attached • Printer server: • Manages print queues (reorder or delete print jobs) • Counts pages • Enforces quotas • Authenticates users • Sets secure printing • Delivers printer drivers to clients • Pushes restrictions to clients (eg force black and white)

23. File server • Can be a role of general server or a standalone server (egFreeNAS, NAS appliance) • LAN server • Accessed via SMB (Server Message Block networking protocol) • Clients request files/folders from the file server • Authentication via Active Directory • Clients can map network drives on a file server to appear as local drives on the client • Internet file server • Accessed via FTP or HTTP

24. email • A mail server contains a message transfer agent (MTA) • A mail user agent (MUA) in a client (such as Outlook, Thunderbird): • Sends an email via SMTP (Simple Mail Transfer Protocol) on port 25 (encrypted on 465 or 587) • Email can be sent between mail servers using the same protocol • A DNS MX record gives the mail server address for that domain • The MTA either forwards to another MTA on another domain or: • Transfers the email to the message delivery agent (MDA) • The MDA transfers it to the recipients mail box • POP3 (Post Office Protocol port 110) or IMAP (Internet message access protocol port 143) is used: • Download mail to the client (POP3) • Display emails directly on the server (IMAP) • Exchange, gmail, Outlook.com use proprietary protocols internally

25. Database • A database server has a database application which: • Provides data base services to clients • Examples are: • Oracle • DB2 • MS SQL Server • MySQL • Ingres • Access and management of the database can be via an application eg: • Microsoft IIS (for MS SQL server) • phpMyAdmin (for MySQL) • Data can be manipulated using SQL (Structured Query Language) via IIS or PHP

26. Virtualisation • All types of servers can be virtualised • See the virtualisation section for details

27. Business application software • Sales - customer relationship management • CRM software helps businesses manage: • customer data • customer interaction • access business information • automate sales • track leads • contracts • marketing • customer support • clients and contacts • support vendor / partner relationships

28. Business application software • Marketing - presentation and communication • Automation tools: • email marketing • website visitor tracking • lead management • social media management • reporting and analytics • integration with webinar and event planning • Presentation tools • Slide shows (PowerPoint, Prezi) • Shared presentations • Online meetings

29. Business application software • Finance - accountancy packages • Records all the financial activity within a business organization • Accounting functions: • accounts payable • accounts receivable • ledger • reporting modules • payroll • Investment choices • Present accurate and updated financial data for every transaction of the business

30. Business application software • Human Resources - employee record management • Retaining • Hiring • Onboarding • Administration • Managing payroll • HR planning • Recruiting • Performance management • Absence management • Grievance handling

31. Business application software • Technical support – helpdesk • point of contact for customers to send their queries • ticketing system that tracks and organizes issues for faster resolution. • aggregates and organizes queries and answers into a knowledge base, such as FAQs or guide articles • dashboard • analytics • escalation handling • online chat

32. Business application software • Communication • email – inter company and external mail • instant chat – text based or voice • VOIP – voice over IP telephony – application runs on regular server • video conference – Skype TeamViewer • Not on syllabus but could be added • Collaboration - Slack, IBM Notes, Google Docs

33. We have covered: • 9.1 Describe the typical client operating system features • 9.2 Explain the typical server operating system features • 9.3 Describe the function of different types of server • 9.4 Explain the key function of business application software