# Day 79: Prometheus Interview Questions (Feb 13, 2024)

### **1\. What is the Architecture of Prometheus Monitoring?**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1706162198527/21f80730-9e5d-495c-b417-bd0ae10939ea.png?auto=compress,format&format=webp align="left")

Prometheus follows a unique and powerful architecture designed for scalability and flexibility. At its core, Prometheus adopts a server-client model. The main components include:

* **Prometheus Server:** This is the central component responsible for collecting and storing time-series data through HTTP pull requests. It also processes alerts, rules, and triggers notifications when necessary.
    
* **Prometheus Storage:** The storage engine is a critical part of Prometheus, managing time-series data efficiently. It utilizes a custom, compressed format for storing data on disk.
    
* **Prometheus Pushgateway:** This optional component allows ephemeral and batch jobs to push their metrics to Prometheus. It simplifies integration for jobs that are not long-lived or may have short lifespans.
    
* **Prometheus Alertmanager:** This module handles alerts sent by Prometheus server, deduplicates, groups, and routes them to the correct receiver (like email, Slack, etc.).
    
* **Instrumented Applications:** Prometheus works by pulling metrics from instrumented applications, which expose endpoints for Prometheus to scrape.
    

### **2\. What are the Features of Prometheus?**

Prometheus boasts an array of features that contribute to its popularity in the monitoring landscape:

* **Multi-dimensional Data Model:** Prometheus embraces a multi-dimensional data model, allowing efficient storage and querying of time-series data, which is crucial for monitoring diverse systems.
    
* **PromQL:** A powerful query language enables users to perform complex queries on collected data, facilitating advanced analysis and troubleshooting.
    
* **Alerting:** Prometheus supports a robust alerting system, providing real-time notifications based on predefined rules and thresholds.
    
* **Scalability:** Its architecture supports horizontal scalability, making it suitable for small setups to large, complex environments.
    
* **Service Discovery:** Prometheus easily integrates with service discovery mechanisms, allowing dynamic monitoring of changing infrastructures.
    

### **3\. What are the Components of Prometheus?**

Prometheus comprises several components that work seamlessly together:

* **Prometheus Server**
    
* **Prometheus Storage**
    
* **Prometheus Pushgateway**
    
* **Prometheus Alertmanager**
    
* **Client Libraries:** Available in various languages, these libraries allow applications to expose metrics for Prometheus to scrape.
    

### **4\. What database is used by Prometheus?**

Prometheus relies on a custom time-series database that efficiently stores and retrieves metrics data. This database is specifically designed for the unique needs of Prometheus, ensuring optimal performance and scalability for time-series data.

### **5\. What is the default data retention period in Prometheus?**

The default data retention period in Prometheus is 15 days. However, this can be customized based on the specific requirements of the monitoring environment.