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Computer Science Articles
Page 6 of 53
Race Condition, Critical Section and Semaphore
Race conditions, Critical Sections, and Semaphores are fundamental concepts in operating systems that deal with process synchronization and coordination. Understanding these concepts is essential for preventing data inconsistency and ensuring proper execution in multi-threaded environments. Race Condition A race condition occurs when multiple processes or threads access shared data simultaneously, and the final result depends on the timing or order of their execution. This unpredictable behavior can lead to inconsistent or incorrect results. Race conditions typically arise when: Multiple processes read and write shared variables The execution order is not controlled At least one process ...
Read MoreStorage Device Hierarchy
Computer storage has components that store computer data. The storage device hierarchy organizes these components based on speed, cost, and capacity. The hierarchy follows a trade-off principle: faster storage is more expensive and has lower capacity, while slower storage is cheaper with higher capacity. Storage Device Hierarchy CPU Registers Cache Memory Primary Storage (RAM) ...
Read MoreComputer Storage Definitions and Notations
Computer storage contains many components that are used to store computer data. Understanding the different types of storage devices and their capacity measurements is essential for working with modern computing systems. Computer Storage Types Computer storage devices are classified into Primary and Secondary Storage devices based on their accessibility by the CPU and data permanence. Computer Storage Hierarchy Computer Storage Primary Storage Secondary Storage ...
Read MoreComputer System Organisation
The computer system is a combination of many parts such as peripheral devices, secondary memory, CPU, device controllers, and a shared memory bus. These components work together to execute programs and handle input/output operations. Computer System Organisation The following diagram shows how the CPU, memory, and I/O device controllers are connected through a common system bus − Computer System Organisation CPU Processor Memory RAM Disk Controller ...
Read MoreTACACS+ Protocol
TACACS+ (Terminal Access Controller Access Control System Plus) is a network protocol that provides centralized authentication, authorization, and accounting (AAA) services for network devices. Developed by Cisco Systems as an enhancement to the original TACACS protocol, TACACS+ separates AAA functions into distinct processes, offering greater security and flexibility for network access control. Unlike protocols that combine multiple functions, TACACS+ treats authentication, authorization, and accounting as independent services. This separation allows administrators to configure granular access policies and provides better control over user permissions on network infrastructure devices like routers, switches, and firewalls. How TACACS+ Works TACACS+ operates ...
Read MoreTCP and UDP Server using Select
When it comes to server-client communication, two protocols are commonly used: TCP and UDP. Transmission Control Protocol (TCP) is a connection-oriented protocol that ensures reliable delivery of data packets between network devices. On the other hand, User Datagram Protocol (UDP) is a connectionless protocol that offers faster data transmission but with no guarantee of delivery or order. In this article, we will explore how to build a server using both protocols in Python programming language. We will also discuss the use of select() function in handling multiple client connections efficiently without the overhead of threading. Setting up the ...
Read MoreTELNET and SSH on Adaptive Security Appliance (ASA)
In today's world where cyber attacks are becoming more frequent and complex, network security is a top priority for businesses. One of the most common ways to manage network security is through the use of firewalls, with Cisco Adaptive Security Appliance (ASA) being one of the most popular firewalls used in enterprise networks. In this article, we will focus on two protocols that are commonly used to manage ASA: TELNET and SSH. Definition of TELNET and SSH TELNET (TErminal NETwork) is a protocol used for remote access to devices over a network. It allows users to connect to ...
Read MoreWhat is bus arbitration in computer organization?
Bus arbitration is a critical mechanism in computer organization that determines which device gets control of the system bus when multiple devices need to access it simultaneously. A bus master is any device that initiates data transfers on the bus. In modern computer systems, multiple bus masters exist, including the CPU, DMA controllers, graphics cards, and network adapters. Since only one device can control the bus at any given time, a systematic approach is needed to manage access. How Bus Arbitration Works When multiple devices request bus access, the arbitration mechanism decides which device gets priority based ...
Read MoreWhat is Time-To-Live (TTL)?
Time to Live (TTL) is a mechanism in computer networking that prevents data packets from circulating indefinitely through a network. It is a field in the IP header that contains a numeric value representing the maximum number of hops (router-to-router jumps) a packet can make before being discarded. When a packet travels through a network, each router it passes through decrements the TTL value by one. Once the TTL reaches zero, the router drops the packet and typically sends an ICMP "Time Exceeded" message back to the sender. This prevents packets from looping forever due to routing errors or ...
Read MoreSSH Meaning in Computer Network
Secure Shell (SSH) is a network protocol that provides secure, encrypted communication between two computers over an insecure network. It is primarily used to access remote devices securely, replacing older protocols like Telnet that transmitted data in plaintext. SSH creates an encrypted tunnel between the client and server, ensuring that all data transmitted remains confidential and protected from eavesdropping or tampering. This makes it an essential tool for system administrators, developers, and anyone who needs secure remote access to networked systems. How SSH Works SSH uses a combination of symmetric and asymmetric encryption to establish secure connections. ...
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