Users can buy high-definition photographs from the website. When a user buys a highdefinition photograph, a Secure Socket Layer (SSL) connection is created.
(i) Give one benefit of using an SSL connection.
One benefit of using an SSL connection is that data is encrypted during transmission, so
sensitive information (such as payment details) cannot be easily intercepted or read by hackers.
Explain how the SSL connection is created.
An SSL connection is created using the following steps:
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The user’s browser requests a secure connection to the website.
The web server sends its SSL certificate to the browser.
The browser checks that the certificate is valid and trusted.
The browser generates a session key and encrypts it using the server’s public key.
The server decrypts this using its private key.
A secure encrypted connection is then established using the session key
What is a session key?
A session key is a temporary encryption key used to encrypt data during a single communication
session.
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It is created when the SSL connection starts
It is used to encrypt and decrypt all data sent between the user and the server
It is discarded after the session ends for security
👉 This makes communication fast and secure because the same key is used on both sides.
DNS Server:
A DNS (Domain Name System) server acts like the Internet’s phonebook. Its main function is
to translate human-readable domain names into IP addresses, which computers use to locate
and communicate with each other on the network.
Here’s a breakdown of its functions:
1. Domain Name Resolution: When you type a website address like www.example.com,
the DNS server converts it into an IP address (e.g., 192.168.1.1) so your browser can
connect to the correct server.
2. Caching: DNS servers recently looked-up addresses temporarily to speed up future
requests and reduce network traffic.
3. Email Routing Support: DNS servers also help direct email by translating domain
names in email addresses into the correct mail server addresses.
4. Load Distribution: Some DNS servers can direct requests to different IP addresses to
balance traffic across multiple servers hosting the same website.
In short, without DNS servers, we would need to remember complex IP addresses instead of
simple domain names to access websites.
DNS servers act as intermediaries that translate domain names into IP addresses, so
your computer can find the correct server to connect to, without you needing to
remember numerical addresses.
Proxy Sever
A proxy server is an intermediary computer or server that sits between a user’s device and the
Internet. Its main job is to forward requests from a client to another server and then send the
responses back to the client.
Here’s a breakdown of its functions:
Functions of a Proxy Server
1. Privacy and Anonymity:
o Hides your IP address when you access websites.
o Websites see the proxy’s IP instead of yours.
2. Content Filtering and Security:
o Can block access to certain websites or content.
o Can scan traffic for malware before it reaches your device.
3. Caching:
o Stores copies of frequently accessed web pages.
o Reduces loading time and saves bandwidth.
4. Bypassing Restrictions:
o Allows access to content blocked in your country or network by routing traffic
through a different location.
5. Logging and Monitoring:
o Organizations can monitor employee internet usage by routing traffic through a
proxy.
✅ In short: A proxy server acts like a middleman between your device and the Internet,
improving privacy, security, and sometimes speed.
Here’s a clear comparison between a DNS server and a proxy server so you can see the
difference:
Feature
DNS Server
Proxy Server
Acts as an intermediary between
Translates domain names (like
your device and the Internet,
Purpose
www.example.com) into IP addresses
forwarding requests and
so your computer can find the server.
responses.
Works at the request/traffic level
Works at the domain name/IP level.
Operation Level
(can inspect and modify data).
Can hide your IP, making your
Does not hide your IP. The website
request appear to come from the
Privacy/Anonymity
knows your IP.
proxy.
Can cache full web content to
Caches IP addresses of domain names
speed up browsing and save
Caching
to speed up lookups.
bandwidth.
Can block or filter websites and
Does not filter content.
Filtering
content based on rules.
Enhance privacy, bypass
Quickly find the IP address of
restrictions, filter content,
Use Cases
websites.
improve performance.
✅ Key Difference in Simple Terms:
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DNS server: “What is the address of this website?”
Proxy server: “I will go fetch this website for you and hide or control how you access
it.”
Firewall: A firewall is a network security system that monitors and controls incoming
and outgoing network traffic based on predetermined security rules. Think of it as a gatekeeper
between your computer (or network) and the Internet.
Functions of a Firewall
1. Traffic Filtering:
o Blocks unauthorized or suspicious traffic.
o Allows only traffic that meets the security rules.
2. Protection Against Hacking:
o Prevents hackers from accessing your network or devices.
o Stops malware from entering or spreading inside the network.
3. Access Control:
o Can restrict access to certain websites, applications, or services.
o Used by organizations to enforce safe internet usage.
4. Monitoring:
o Logs network activity for analysis and detecting potential threats.
Types of Firewalls
1. Hardware Firewall:
o A physical device installed between your network and the Internet (common in
offices).
2. Software Firewall:
o A program installed on a computer to protect that device specifically.
3. Next-Generation Firewall (NGFW):
o Combines traditional firewall features with advanced functions like application
control, intrusion prevention, and threat intelligence.
✅ In short: A firewall protects your network or device from unauthorized access and
cyber threats, while still allowing legitimate communication.
Here’s how a firewall, DNS server, and proxy server work together in a network, step by step:
1. User Request
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You type a website address (e.g., www.example.com) in your browser.
2. DNS Server Resolves the Address
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The DNS server translates www.example.com into an IP address so your computer knows
where to connect.
3. Proxy Server Forwards the Request (Optional)
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If your network uses a proxy server, your request goes through it.
The proxy can hide your IP, filter content, or cache pages for faster access.
4. Firewall Checks the Traffic
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Before the request reaches the Internet, the firewall examines it:
o Is it coming from a trusted device?
o Is it going to a safe IP or port?
o Does it meet security rules?
If it passes the rules, the request is allowed.
If not, the firewall blocks the traffic to protect the network.
5. Response Comes Back
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The web server sends the data back:
o First through the firewall, which checks it again.
o Then through the proxy (if used), which may cache or filter content.
o Finally, it reaches your computer.
✅ Summary:
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DNS server: “What is the IP address of this website?”
Proxy server: “I will fetch the website for you, and I can hide/filter/cache it.”
Firewall: “Is this traffic safe? Can it enter or leave the network?”