Networking

Question 1

TCP/IP

Answer 1

Application layer: the group of applications that require network communication. This is what the user typically interacts with, such as email and messaging.

Transport layer: responsible for providing a solid and reliable end-to-end connection between the original application or device and its intended destination. This is the level where data is divided into packets and numbered to create a sequence. TCP or UDP

Internet: Responsible for connecting independent networks to transport the packets across network boundaries

Data link Layer: defines how data should be sent, handles the physical act of sending and receiving data, and is responsible for transmitting data between applications or devices on a network. Includes ethernet and network interface cards.

Question 2

How does the internet work?

Answer 2

Network of computers linked together. The connections are a mixture of copper cables, fiber optic cables, wireless radio connections and satellite links.
The role of the internet to transfer data from one place to another. It does this by a process called packet switching. This is made possible by two things.
hardware that consists of copper cables, fiber optics, and wireless radio connections.
and protocols which are a set of rules that govern how entities communicate. An example is tcp/ip

Question 3

How does DNS work?

Answer 3

• Computer first checks its own cache memory. If it can not find it, it will send a query to the resolver server which is typically managed by the users ISP
• The revolver checks its own cache memory for the given domain name. If it cant find it then it forwards the request to the root name server.
• The root name server then forward the request for the domain to one of the top level domain servers for .com.
• the name server for .com then directs the resolver to the authoritative name server which holds a copy of all domain names and associated IP addresses for a region.
• The authoritative name server then returns the IP address to the DNS resolver
• The resolver returns the IP address to the browser as well as caching the IP address .

Question 4

What is DNS used for?

Answer 4

Resolves human readable domain names to IP addresses

Question 5

Examples of DNS records

Answer 5

SOA(start of authority)

Question 6

What’s a (SSL) certificate supposed to do?

Answer 6

It’s a digital certificate that authenticates a website’s identity & enables an encrypted connection

Question 7

Name a network control protocol?

Answer 7

DHCP

Question 8

What does DCHP do?

Answer 8

DHCP is used to automate the process of configuring devices with ip addresses

Question 9

TCP vs UDP

Answer 9

TCP is a connection orientated protocol(reliable delivery; recovery from errors) where as udp is connection less. Udp is quicker and less secure than tcp as it doesn’t require two conversations before sending actual data.

Question 10

Why does UDP exist? In what type of applications is it helpful?

Answer 10

faster transmission as it enables the transfer of data before an agreement is provided by the receiving party.

VoIP, DNS lookup, online games

Question 11

What is a VPN?

Answer 11

VPN is a virtual private network that has encrypted data traversing a public network

Question 12

What is data deduplication?

Answer 12

Is a process that eliminates redundant data in a data set. Reduces storage and bandwidth demand.

Question 13

What happens when you type an address on a browser and hit enter?

Answer 13

The browser looks up the IP address for the domain name by using DNS which is basically a database that maps IP addresses to domain names.
Then the browser initiates a TCP connection with the server.
The browser then sends an HTTP request to the server and the server processes the request and sends back a response

Question 14

What is load balencing?

Answer 14

Distributes load to multiple servers.
Allows for large-scale implementations and fault-tolerance

Question 15

Horizontal scaling vs vertical scaling

Answer 15

Horizontal scaling means to add more machines to your pool of resources where as vertical scaling keeps the existing infrastructure and adds more computing power.

Question 16

What method would you use to sync the clock on a group of (possibly) different machines? (the clock used by the operating system)

Answer 16

network time protocol: clock synchronization between computer systems over packet-switched, variable-latency data networks.

Question 17

Difference between IPv4 and IPv6?

Answer 17

IPv4 is a 32-Bit IP address, whereas IPv6 is a 128-Bit IP address.
IPv4 is a numeric addressing method, whereas IPv6 is an alphanumeric addressing method.
IPv4 binary bits are separated by a dot(.), whereas IPv6 binary bits are separated by a colon(:).
IPv4 supports broadcast, whereas IPv6 doesn’t support broadcast.

IPv6 also uses NDP (neighbor discovery protocol)
and Operates using multicast with ICMPv6
Uses SLAAC, which automatically configures IP addresses without the need for DHCP server

Question 18

What are the networking layers?

Answer 18

Physical, data, network, transport, session, presentation, application

Question 19

Different HTTP methods?

Answer 19

POST - create new resources
GET - retrieve data
DELETE - delete

Question 20

How does DHCP work?

Answer 20

DHCP Discover sent via broadcast to DHCP server using udp port 68
DHCP Offer sent via broadcast to client using udp port 67
DHCP Request sent to DHCP server using udp port 68
DHCP Acknowledgement sent to client using udp port 67

Question 21

What is a CDN

Answer 21

A content delivery network (CDN) is a network of interconnected servers that speeds up webpage loading for data-heavy applications. It brings data closer to where the users are. It does this by caching the website content and storing a version of it at an edge location

Question 22

How is information transmitted from digital bits to an end user?

Answer 22

Data starts at the physical layer as bits

Question 23

What is edge computing

Answer 23

Edge computing is a distributed computing paradigm that brings computation and data storage closer to the sources of data. This is expected to improve response times and save bandwidth.

Question 24

What is tcip/ip

Answer 24

a set of protocols that standardises how information is transmitted across the internet

Question 25

What is virtulisation?

Answer 25

allows the hardware elements of a single computer to be divided into multiple virtual computers, commonly called virtual machines (VMs). Each VM runs its own operating system (OS) and behaves like an independent computer

Question 26

What is the hypervisor layer?

Answer 26

a form of virtualization software that creates and runs virtual machines. It allows for multiple VMs to run on single host system

Question 27

Give a use case for edge computing.

Answer 27

Self-driving cars: Autonomous vehicles need to react in real time, without waiting for instructions from a server.

Question 28

Give a benefit of using a cache layer

Answer 28

Increase data retrieval performance by reducing the need to access the underlying slower storage layer.

Question 29

WHat is parralleism?

Answer 29

Techniques to make programs faster by performing several computations at the same time. This requires hardware with multiple processing units.

Question 30

What is ECS?

Answer 30

Amazon Elastic Container Service.
highly scalable and fast container management service. You can use it to run, stop, and manage containers on a cluster.

Question 31

How do SSL certificates work?

Answer 31

1. Browser connects to a web server secured with SSL (https). Browser requests that the server identify itself.
2. Server sends a copy of its SSL Certificate, including the server’s public key.
3. Browser checks the certificate against a list of trusted certificate authorities and that the certificate is valid. If the browser trusts the certificate, it creates, encrypts, and sends back a symmetric session key using the server’s public key.
4. Server decrypts the symmetric session key using its private key and sends back an acknowledgement encrypted with the session key to start the encrypted session.
5. Server and Browser now encrypt all transmitted data with the session key.

Question 32

How is information transmitted from digital bits to an end user?

Answer 32

Data starts at the physical layer in the form of bits and the job of the physical layer is to transmit individual bits to the next node. When a computer has received data, it will convert it to 0s and 1s and send it up the data link layer.
At this layer the information is encapsulated in what is called an ethernet frame and adds the mac addresses of both the sender and receiver and then this information is sent to the networking layer in what is called a packet.
At this layer which is responsible for routing the information to the correct destination, it adds the ip addresses of both the sender and receiver in the header and the segment is sent to the transport layer. The transport layer is responsible for end-to-end delivery of a complete message. Here is where you will you use either TCP or UDP depending on the type of message. The transport layer reads the port number and then sends the data to it’s respective application. The session layer is responsible for communication between devices. Then at the presentation layer is where you will have character encoding and encryption. Finally, the application layer is what the end user interacts with.