Update README.md (#10228)

Added answers to the questions in "System Design"

Co-authored-by: Amogha Kancharla <133768988+amoghak-ds@users.noreply.github.com>

README.md

@@ -3315,7 +3315,9 @@ Bonus: extract the last word of each line
 ## System Design
 
 <details>
-<summary>Explain what is a "Single point of failure"?</summary><br><b>
+<summary>Explain what a "single point of failure" is. </summary><br><b>
+A "single point of failure", in a system or organization, if it were to fail would cause the entire system to fail or significantly disrupt it's operation. In other words, it is a vulnerability where there
+is no backup in place to compensate for the failure.
 </b></details>
 
 <details>
@@ -3342,10 +3344,34 @@ In multi-CDN, content is distributed across multiple different CDNs, each might
 
 <details>
 <summary>Explain "3-Tier Architecture" (including pros and cons)</summary><br><b>
+A "3-Tier Architecture" is a pattern used in software development for designing and structuring applications. It divides the application into 3 interconnected layers: Presentation, Business logic and Data storage.  
+PROS: 
+* Scalability
+* Security
+* Reusability
+CONS:
+* Complexity
+* Performance overhead
+* Cost and development time
 </b></details>
 
 <details>
 <summary>Explain Mono-repo vs. Multi-repo.What are the cons and pros of each approach?</summary><br><b>
+In a Mono-repo, all the code for an organization is stored in a single,centralized repository.
+PROS (Mono-repo):
+* Unified tooling
+* Code Sharing
+CONS (Mono-repo):
+* Increased complexity
+* Slower cloning
+
+In a Multi-repo setup, each component is stored in it's own separate repository. Each repository has it's own version control history.
+PROS (Multi-repo):
+* Simpler to manage
+* Different teams and developers can work on different parts of the project independently, making parallel development easier.
+CONS (Multi-repo):
+* Code duplication
+* Integration challenges
 </b></details>
 
 <details>
@@ -3354,6 +3380,7 @@ In multi-CDN, content is distributed across multiple different CDNs, each might
 * Not suitable for frequent code changes and the ability to deploy new features
 * Not designed for today's infrastructure (like public clouds)
 * Scaling a team to work monolithic architecture is more challenging
+* If a single component in this architecture fails, then the entire application fails.
 </b></details>
 
 <details>
@@ -3365,16 +3392,17 @@ In multi-CDN, content is distributed across multiple different CDNs, each might
 
 <details>
 <summary>What's a service mesh?</summary><br><b>
-
+It is a layer that facilitates communication management and control between microservices in a containerized application. It handles tasks such as load balancing, encryption, and monitoring.
-[This article](https://www.redhat.com/en/topics/microservices/what-is-a-service-mesh) provides a great explanation.
 </b></details>
 
 <details>
 <summary>Explain "Loose Coupling"</summary><br><b>
+In "Loose Coupling", components of a system communicate with each other with a little understanding of each other's internal workings. This improves scalability and ease of modification in complex systems.
 </b></details>
 
 <details>
 <summary>What is a message queue? When is it used?</summary><br><b>
+It is a communication mechanism used in distributed systems to enable asynchronous communication between different components. It is generally used when the systems use a microservices approach.
 </b></details>
 
 #### Scalability