Network Load Balancing and Network Security: PECTAA Class 12 Computer Science, Punjab Board

On result day, thousands of students open the same board website at once. If one server took every request, it would slow down or fail. Sharing the load keeps it running, and security keeps it safe from people who should not get in. Sections 1.13 and 1.14 of the book cover both.

Chapter 1 of the PECTAA Computer Science 12 book covers computer networks. After network diagnostics and performance (sections 1.11 and 1.12), section 1.13 covers network load balancing and section 1.14 network security. This note is for FSc Part 2 (2nd year, Class 12) students in Lahore, Faisalabad, Sargodha, Rawalpindi, Multan, Gujranwala and the other Punjab boards. Gujrat district comes under the Gujranwala board. PECTAA writes the books. Your own board sets your paper.

What to know

Load balancing (section 1.13). Load balancing manages network traffic by distributing work among multiple servers or links. This stops any one device being overloaded. It improves speed and reliability, is used in large networks and data centres, and helps networks handle more users.

Benefits.

• Better network speed and response time.
• Lower risk of service failure: if one server fails, the others keep working.
• A better user experience.
• High traffic is handled more easily.
• Greater reliability and availability.

Basic methods.

• Round Robin: sends requests to the servers one by one, in turn.
• Least Connection: sends traffic to the server that is less busy.
• IP Hash: uses the client's IP address to decide which server receives the traffic.

The book notes that these simple methods are easy to implement.

Network security (section 1.14). Network security protects computer networks and keeps data safe from unauthorised access. It helps prevent data loss and damage, keeps information private, protects devices from malware and stops hackers entering. Homes and organisations both need basic security measures.

Firewalls. A firewall is a security device or software that controls incoming and outgoing traffic. It blocks harmful or unwanted data (Figure 1.17) and acts as a barrier between safe and unsafe networks. Firewalls are used in homes and offices.

Encryption. Encryption turns data into a secret form that only authorised users can read. It protects data while it is being transferred and is used in email and online services that handle private information. Strong encryption helps prevent data theft.

Access control. Access control decides who may use the network and lets in only authorised users. Usernames and passwords are the common method. Permissions limit what each user can do, protecting important resources.

Common threats.

• Viruses and malware: damage systems.
• Hackers: try to steal data.
• Phishing: tricks users into sharing information.
• Denial of Service (DoS): stops network services working.

Security tools help reduce these threats.

Key points

• Load balancing spreads work; it is about speed and reliability.
• Round Robin takes turns; Least Connection picks the least busy; IP Hash uses the address.
• Firewall = traffic barrier; encryption = secret form; access control = who gets in and what they may do.
• Phishing targets people; DoS targets services.

Worked examples

Example 1 (Round Robin). Three servers A, B and C receive requests 1 to 7 in Round Robin order. Which server handles request 7?

1. Order: 1 → A, 2 → B, 3 → C, 4 → A, 5 → B, 6 → C, 7 → A.
2. Request 7 goes to server A (7 leaves a remainder of 1 when divided by 3).

Example 2 (Least Connection). Server A has 12 open connections, B has 5 and C has 9. Where does the next request go?

1. Least Connection picks the least busy server.
2. B, with 5 connections.

Example 3 (match the threat). An email asks a student to "confirm" an account password on a look-alike page.

1. The aim is to trick the user into giving information.
2. This is phishing. Defence: never share passwords; check the sender and the address of the page.

Example 4 (book Class Activity). How does security protect sensitive data such as patients' CT scans in a hospital?

1. Access control: only doctors and staff with accounts and the right permissions can open the scans.
2. Encryption: scans sent between departments or hospitals stay unreadable to outsiders.
3. Firewall: blocks unwanted traffic from outside reaching the hospital's servers.
4. Together these keep the records private and prevent loss or damage.

Common mistakes in the exam

1. Calling load balancing a security tool. Its job is spreading traffic for speed and reliability.
2. Mixing Round Robin and Least Connection. One takes turns; the other checks how busy each server is.
3. Saying a firewall encrypts data. It filters traffic; encryption is separate.
4. Treating DoS as data theft. DoS stops services; it is not mainly about stealing.
5. Listing threats without the matching protection when the question asks for both.

Exam technique

• Define, then give one benefit or one example, for each term.
• Use a short table to compare the three load balancing methods.
• Pair each threat with a defence from the book: firewall, encryption or access control.
• Check your board's notice for the sections in your paper.

Practice questions

1. Give two benefits of load balancing. Answer: Faster response time and higher reliability (if one server fails, others continue).
2. Which method uses the client's IP address? Answer: IP Hash.
3. What is the role of permissions in access control? Answer: They limit what each user can do.
4. Name the threat that stops network services. Answer: Denial of Service (DoS).
5. Is a firewall hardware or software? Answer: It can be either: a security device or software.

Ready to practise this? Continue in 2nd Year Computer Science.