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+Here is a quick recap of AWS Route 53 based on the sources, presented point-wise for your interview preparation:
+
+*   **What is Route 53?** AWS provides **DNS (Domain Name System) as a service** through Route 53. Think of it like AWS providing compute as a service (EC2) or Kubernetes as a service (EKS).
+*   **What is DNS?** DNS stands for Domain Name System. Its primary function is to **map human-readable domain names (like amazon.com or flipkart.com) to computer-readable IP addresses**.
+*   **Why is DNS needed?**
+    *   **Ease of use:** Domain names are much **easier for people to remember** than complex IP addresses like `3.6.10.171`.
+    *   **Flexibility:** IP addresses can **change** (they can be dynamic). Using a domain name provides a stable address even if the underlying IP address changes.
+*   **How DNS works (Simply put):** A DNS service **keeps records** that map a domain name to its corresponding IP address.
+*   **How Route 53 fits into AWS architecture:**
+    *   In a typical setup (like applications in a private subnet behind a load balancer in a public subnet), when a user tries to access an application using its domain name (e.g., amazon.com), **Route 53 is the first service to intercept the request**.
+    *   Route 53 looks up the domain name in its records to find the associated IP address, usually the **IP address of a load balancer**.
+    *   Once the domain name is resolved to the IP address, the request is **forwarded to the load balancer** (and then typically to the application instances).
+*   **Key Components/Features of Route 53:**
+    *   **Domain Registration:** You can **register (buy) domain names directly through AWS Route 53**. You can also integrate domain names purchased from other registrars (like GoDaddy).
+    *   **Hosted Zones:** This is a critical concept in Route 53. **Hosted zones contain the DNS records** for a specific domain name. When Route 53 receives a request for a domain name, it looks for the DNS records in the relevant hosted zone (which can be public or private) to resolve the domain name to an IP address.
+    *   **DNS Records:** These are the actual mappings within a hosted zone that **link a domain name or subdomain to an IP address** or other destination.
+    *   **Health Checks:** Route 53 can **monitor the health of your web applications or web servers** (e.g., checking if they are active every minute or five minutes). It can use this information to determine where to forward requests, potentially performing some kind of balancing across healthy servers.
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+Route 53 simplifies the complex process of managing DNS, especially when hosting applications on AWS.# Route53
+
+TODO

day-009/Quick-Interview-Recap.md

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+**AWS S3 Quick Interview Recap**
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+| Concept | Description | Key Detail/Benefit |
+| --- | --- | --- |
+| **What is S3?** | Amazon S3 stands for **Simple Storage Service**. It is a **storage service** provided by AWS. | It is one of the most **easy services to learn** on AWS. Many people start their AWS journey with S3 because it's simple to understand and execute. |
+| **Purpose** | S3 solves the very common problem of **storage** for organizations. | Organizations deal with large amounts of data like heavy databases, continuous backups, application logs, dashboards, chats, CSV files, and Excel sheets. S3 provides a solution for where organizations can save all these things, especially when moving to the public cloud. |
+| **Key Characteristics** | S3 possesses five important characteristics. | These are **highly scalable, highly available, security, cost efficiency, and performance**. These characteristics are major factors behind S3's popularity. |
+| **Reliability & Durability** | How robust S3 is against data loss. | S3 is **99.999999999% (Eleven Nines)** reliable and durable. If you upload one billion objects over 100 years, you can expect **only one object to potentially be lost**. This is achieved by creating **multiple replicas** of objects across different Availability Zones and Data Centers within a region. Your data is almost guaranteed to never get deleted. |
+| **Availability** | How often the data stored in S3 is accessible. | S3 Standard storage class offers **99.9% availability**. |
+| **Scalability** | The ability of S3 to handle vast and growing amounts of data. | S3 is **highly scalable**. There is **no restriction on the amount of data** that can be stored in an S3 bucket. You can keep uploading as much data as required, and AWS S3 will not restrict you. |
+| **Objects & Buckets** | The fundamental components of S3 storage. | A **Bucket** is what you create in the S3 service, acting as a container for your data. An **Object** is anything you store inside a bucket, such as pictures, videos, files, folders, Excel sheets, reports, application logs, database dumps, configuration files, etc.. **Each object cannot be more than 5 TB** in size, but you can store multiple objects. |
+| **Bucket Naming** | The rules for naming an S3 bucket. | S3 bucket names **must be globally unique** across all AWS accounts. This is because anything uploaded to S3 can be globally accessible. DevOps engineers often use a naming standard to ensure uniqueness. |
+| **Regional Scope** | Although content is globally accessible, buckets are tied to a specific AWS region. | S3 buckets are **scoped in a region**, similar to EC2 instances. You select a region when creating a bucket. Choosing a region nearer to the users can result in **less latency**. |
+| **Global Accessibility** | How data stored in S3 can be reached from anywhere. | Content put on S3 is **globally accessible**. Objects can be accessed using the **HTTP/HTTPS protocol** via a URL. You can share the URL and grant permissions for access. |
+| **Public Access Block** | A security feature to prevent accidental public exposure of data. | By default, **Public Access is blocked** for new buckets. This is highly recommended to keep enabled, especially for sensitive data. You must **disable this block** if you intend to host a public static website. |
+| **Security Features** | Mechanisms to secure data stored in S3. | S3 offers various security options including **encryption** (at rest and in transit), Access Control Lists (ACLs), **Bucket Policies** to restrict permissions, Object Locking, and **Access Logging** to monitor who accesses buckets. These allow fine-grained control over who can access your data. |
+| **Cost Efficiency** | How the cost of using S3 compares to other storage options. | AWS S3 is considered **very cheap and cost-effective**. The cost depends on the **storage class** selected. Hosting a static website on S3 can be very cheap compared to other platforms. |
+| **Storage Classes** | Different options for storing data based on access frequency and cost requirements. | S3 offers **multiple storage classes** (e.g., Standard, Standard-IA, Glacier, Deep Archive). The choice depends on whether you prioritize **cost effectiveness or access time**. Glacier Deep Archive is the cheapest but has the longest retrieval time (12-48 hours). |
+| **Performance** | The speed at which data can be uploaded to and downloaded from S3. | S3 offers good performance. Using a bucket in a nearby region reduces latency. S3 supports **Multi-Part Uploads**, which helps upload large files efficiently and can retry parts if there are interruptions. |
+| **Versioning** | A feature that allows keeping multiple versions of an object. | S3 supports **versioning**. When enabled on a bucket, S3 keeps a copy of the previous version whenever an object is modified or deleted. This allows you to **retrieve old versions** of objects. Versioning can be combined with storage classes and lifecycle policies for cost management (e.g., moving old versions to cheaper storage or deleting them). |
+| **Static Website Hosting** | Using an S3 bucket to host a static website. | S3 can host static websites because its content is globally accessible. This requires enabling the static website hosting option on the bucket properties, specifying an index document (like `index.html`), disabling the 'Block All Public Access' setting, and adding a **bucket policy** to allow public `s3:GetObject` permissions. It is a **cheap solution** for hosting static sites. **CORS** might need to be enabled for JavaScript making external API calls. |
+| **Bucket Policies** | JSON documents used to grant or deny permissions for accessing S3 buckets and their objects at the bucket level. | Bucket policies are a crucial part of S3 **permissions**. They allow you to control access even for users who might have broad S3 permissions via IAM. For example, you can use a bucket policy to **restrict access for everyone except the bucket owner**. You can use a policy generator to help write the JSON. This is an important responsibility for devops engineers. |