Design a web crawler that fetches every page on en.wikipedia.org exactly 1 time. You have 10,000 servers you can use and you are not allowed to fetch a URL more than once. If a…
Category: Tech Interviews
System Design – Notification System
Designing a system similar to Twilio, which is a cloud communications platform, requires careful planning and architecture to ensure high availability, scalability, and fault tolerance. Some basic requirements: Below is an overview…
How DNS work, take google.com as example
DNS, or Domain Name System, is a crucial component of the internet, acting as the phonebook of the internet. It translates human-friendly domain names (like “google.com”) into IP addresses that computers use…
System Design – A Distributed High-throughput Counter
Designing a high-throughput, scalable counter system with a focus on write-heavy operations involves several key components and considerations. Now, the system needs to handle a large volume of write operations (1M writes/sec)…
Linux Commands Examples
nslookup nslookup is a cross-platform command-line tool for querying the Domain Name System (DNS). Purpose Command Basic DNS Lookup nslookup example.com Find Mail Servers for a Domain nslookup -type=mx example.com Query Specific…
Hard link and Soft link
In Unix-like operating systems, hard links and soft links (also known as symbolic links) are two types of links that can be created to reference files. They serve different purposes and have…
Zombie Process
In Linux and other Unix-like operating systems, a “zombie” process, or defunct process, is a process that has completed execution but still has an entry in the process table. This occurs when…
Signals in Linux
Linux signals are a mechanism used for inter-process communication in Unix and Unix-like operating systems, such as Linux. They are used to notify a process that a specific event has occurred, such…
Some common HTTP headers
HTTP headers are an integral part of HTTP requests and responses, providing essential context about the data being transferred. Here are some common HTTP headers along with explanations for each: 1. Connection:…