Access Control

What is Role-Based Access Control (RBAC) in Database Security?

Role-Based Access Control (RBAC) is a database security model where permissions are granted to named roles rather than to individual users, and users gain thei…

How Do You Implement Row-Level Security in a Database?

Row-level security (RLS) is implemented by attaching a security policy to a table that filters which individual rows a given user or role can see or modify, en…

What is the Proxy Pattern?

The Proxy pattern provides a surrogate object that implements the same interface as a real subject and controls access to it, allowing extra logic such as lazy…

Decorator vs Proxy Pattern

The Decorator pattern wraps an object to add new responsibilities or behavior on top of what it already does, while the Proxy pattern wraps an object to contro…

What is a Friend Class in C++?

A friend class in C++ is a class explicitly granted access to another class’s private and protected members, declared using the `friend` keyword inside the cla…

Friend Functions vs Encapsulation

A friend function is a non-member function explicitly granted access to a class’s private and protected members, and it appears to conflict with encapsulation…

What Are the Basic Security Mechanisms in an Operating System?

An operating system enforces security through authentication (verifying who a user is), authorization (deciding what an authenticated user may do via permissio…

What Are Access Control Lists (ACLs) in an Operating System?

An access control list (ACL) is a per-object list of entries, each pairing a specific user or group with the permissions they hold on that object, giving finer…

What Is Capability-Based Security in an Operating System?

Capability-based security is an access control model where a process’s right to perform an operation on an object is represented by an unforgeable token, calle…

What is a Firewall?

A firewall is a network security system that monitors and controls incoming and outgoing traffic based on a defined set of rules, sitting between a trusted int…

What is TACACS+?

TACACS+ (Terminal Access Controller Access-Control System Plus) is a Cisco-designed AAA protocol that fully encrypts the entire packet body and separates authe…

What is Kerberos in Networking?

Kerberos is a network authentication protocol that uses trusted third-party ticket-granting servers and symmetric-key cryptography to let clients and services…

Site-to-Site vs Remote-Access VPN: What is the Difference?

A site-to-site VPN permanently connects two whole networks (such as a branch office and a data center) through gateway devices so that every user behind either…

What is Network Segmentation?

Network segmentation is the practice of dividing a network into smaller, isolated segments — using VLANs, subnets, firewalls, or software-defined policies — so…

What is Zero Trust Networking?

Zero Trust Networking is a security model built on the principle "never trust, always verify" — no device, user, or service is implicitly trusted just because…

What is a Network Firewall Rule?

A network firewall rule is a single ordered instruction — matching criteria like source/destination IP, port, and protocol, plus an action of allow or deny — t…

Stateful vs Stateless Firewall: What is the Difference?

A stateful firewall tracks the full context of each active connection and automatically permits return traffic belonging to an already-approved session, while…

What is an Intrusion Prevention System (IPS)?

An Intrusion Prevention System (IPS) is an inline network security device that inspects live traffic in real time and, upon matching a known attack signature o…

How Would You Design Google Drive?

Designing Google Drive builds on a chunked-storage-and-sync foundation like Dropbox but adds a real-time collaborative editing layer, where concurrent edits to…

What is a Kubernetes Namespace and When Should You Use One?

A Kubernetes Namespace is a virtual cluster partition that scopes resource names, access control, and resource quotas, letting multiple teams or environments s…

What is Kubernetes RBAC and How Does It Work?

Kubernetes RBAC (Role-Based Access Control) is an authorization mechanism that grants subjects — users, groups, or service accounts — permission to perform spe…

What is a Kubernetes ServiceAccount?

A Kubernetes ServiceAccount is an identity that Pods use to authenticate to the Kubernetes API server, distinct from user accounts that human operators use, an…

How Do You Manage Secrets in a DevOps Pipeline?

Secrets management means storing credentials, API keys, and certificates in a dedicated secrets store with encryption, access control, and audit logging, then…

What is HashiCorp Vault and How Does It Work?

HashiCorp Vault is a centralized secrets-management system that securely stores, dynamically generates, and tightly controls access to credentials, encryption…