2016 paper

Question 1

How can client send data to the server?

Answer 1

HTTP

Websockets

Question 2

Why does programming in JavaScript involve the extensive use of callback
functions?

Answer 2

• ensures certain code doesnt execute until other code has finished
• everything works in same order
• real time applications

Question 3

What is the Same Origin Policy?

Answer 3

restricts how a document or script loaded from one origin can interact with a resource from another origin

Question 4

Purpose or Same Origin Policy

Answer 4

isolates potentially malicious documents

Question 5

What are the advantages and disadvantages of using libraries and frameworks
for the development of web applications?

Answer 5

• time saving
• scalable
• robustness
  X- not learning how to code
  X - need to understand

Question 6

What are the differences between web browsers and Node.js as JavaScript
runtime environments?

Answer 6

• Node.js executes server side
• browser executes client side
• Node processes the object request, browsers process response objects

Question 7

Briefly describe the relationship between TCP, HTTP and WebSockets

Answer 7

WebSocket is a protocol providing a full duplex communication over a single TCP connection, whereas HTTP provides a half duplex, most HTTP travels over TCP

Question 8

Name two different ways for maintaining state in a web-based application

Answer 8

cookies

web storage

Question 9

What is a Content Delivery Network?

Answer 9

A content delivery network (CDN) is a system of distributed servers (network) that deliver pages and other web content to a user, based on the geographic locations of the user, the origin of the webpage and the content delivery server.

Question 10

What is bandwidth?

Answer 10

maximum rate of data transfer across a given path, over a given period of time

Question 11

What does it mean to say that a layer presents an abstraction of a network?

Answer 11

It is a generalisation of a conceptual model or algorithm, away from any specific implementation

Question 12

What is a routing decision

Answer 12

a decision that direct network packets from their source towards their destination through forwarding decisions

Question 13

What is meant by the default route for a router?

Answer 13

route of packet forwarding when no specific route can be determined for a given IP address

Question 14

What is an authoritative name server?

Answer 14

An authoritative Nameserver is a nameserver (DNS Server) that holds the actual DNS records (A, CNAME, PTR, etc) for a particular domain/ address

Question 15

What are checksums intended to guarantee?

Answer 15

If there has been any error/tampering in transmission or storage

Question 16

how the use of Network Address Translation (NAT) helps us to

not run out of IP addresses

Answer 16

restricts the number of public address a company can use

Question 17

How does Carrier Sense/Multiple Access (CSMA) manage the communication of
packets over a wireless network?

Answer 17

checks the traffic before sending

Question 18

What is a single page application?

Answer 18

an app which works inside a browser and does not require page reloading during use

Question 19

Describe the advantages that a single page web application model has
over the traditional client-server model for web applications.

Answer 19

• fast, most resources only loaded once
• no need to write code to render pages onto server
• can cache any local storage efficently

Question 20

Why is Node.js so popular?

Answer 20

• uses javascript as its main language to build web applications
• uses V8 which can compile and run JS very fast
• single language, JS used on client and server
• easy to modifiy as bunch of small applications

Question 21

Why does callback hell occur?

Answer 21

because the only way in JS to delay a communication so that it runs after the asynchronous call returns is to put delayed code inside a callback function

Question 22

How to avoid callback hell?

Answer 22

• use modules
• aintain better separation of code
• use promises

Question 23

2 parts of an IP?

Answer 23

network and host