DNS & Web Hosting

Domain Name Service (DNS)

When a client sends a request to the server, it has to use an Internet Protocol (IP) address so that we can find the correct server. Modern web browsers allow us to enter a domain name instead, which the DNS translates.

Why use the DNS?

Domain names are much easier to read and remember than IP addresses.
Computers have to use IP addresses to communicate over the Internet Protocol.
The DNS converts these domain names into IP addresses for us.

DNS lookup

When we have a domain name, we send a request to the nearest DNS server asking for the IP address associated with that domain name.
The DNS server responds with the correct IP address.
The client can then use this IP address to send their original request.

DNS miss

If a DNS server does not have an IP address associated with a particular domain name (a DNS miss), then it can ask other DNS servers that it knows about.
By continuing to ask other, larger DNS servers, we will eventually resolve the IP address and send this to the original client.

Web Hosting

Web hosting is the act of keeping a website on a server, and allowing clients to request to see the pages of the website.

Websites

A website is a collection of webpages which are linked together using hyperlinks.
A user can click on hyperlinks to navigate the website.

Hosting a website

A web server is a dedicated computer on the Internet which responds to HyperText Transfer Protocol (HTTP) requests by returning webpages.

Setting up a web server

Some people choose to host their own website, but this can be difficult for many reasons:
- There are a lot of security risks.
- It can be difficult to make sure that the server does not go down, for example if there is a power cut.
- Web servers are expensive.

Hosting providers

Most people opt to use a web hosting company. A web hosting company will charge a monthly fee in return for hosting your site for you.
Web hosting companies will:
- Host your website.
- Regularly back up your site.
- Apply security patches for you.

1Components of a Computer

1.1Structure & Function of the Processor

1.1.1Structure of the CPU

1.1.2Fetch, Decode, Execute Cycle

1.1.3Factors Affecting CPU Performance

1.1.4CPU Architecture

1.2Types of Processors

1.2.1CISC & RISC

1.2.2Multicore & Parallel Cores

1.3Input, Output & Storage

1.3.1Computer Systems

1.3.2Magnetic Storage

1.3.3Optical Storage

1.3.4Types of Optical Storage

1.3.5Types of Memory

1.3.6Flash Memory

1.3.7Virtual Memory

2Software & Software Development

3Exchanging Data

4Data Types, Data Structures & Algorithms

4.1Data Types

4.1.1Data Types

4.1.2Arrays & Strings

4.1.3Representing Numbers

4.1.4Binary Arithmetic

4.1.5Hexadecimal

4.1.6Converting Binary Numbers

4.1.7Floating Points in Binary

4.1.8Floating Point Arithmetic

4.1.9Bitwise Manipulation

4.1.10Character Sets

4.2Data Structures

4.2.1Arrays, Linked Lists & Queues

4.2.2Graphs, Hash Tables & Stacks

4.2.3Trees

4.3Boolean Algebra

4.3.1Computational Logic

4.3.2Boolean Logic

4.3.3Karnaugh Maps

4.3.4Boolean Identities

4.3.5Flip Flops & Adder Circuits

5Legal, Moral, Cultural & Ethical Issues

5.1Computing Related Legislation

5.1.1Data Protection Act (1998)

5.1.2Computer Misuse Act (1990)

5.1.3Copyright Designs and Patents Act (1988)

5.1.4Regulation of Investigatory Powers Act (2000)

5.2Moral & Ethical Issues

5.2.1Online Activity Tracking

5.2.2Censorship

5.2.3Cultural Issues

5.2.4Environmental Issues

5.2.5Layout, Colour Paradigms & Character Sets

6Elements of Computational Thinking

6.1Thinking Abstractly

6.1.1Abstraction

6.2Thinking Procedurally

6.2.1Decomposition

6.3Thinking Logically

6.3.1Pseudocode & Flow Diagrams

7Problem Solving & Programming

7.1Programming Techniques

7.1.1Programming Fundamentals

7.1.2Modularity

7.2Programming Construction

7.2.1Integrated Development Environments

7.2.2Testing

8Algorithms

8.1Algorithms

8.1.1Interpreting, Correcting & Completing Algorithm

8.1.2Sort Algorithms

8.1.3Insertion & Merge Sort

8.1.4Search Algorithms

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