8/3refactor: transform IAP tests to call actual service methodsReplace duplicated business logic tests with real TAPService method callsAdd comprehensive error scenario testing for production edge casesRestructure test files for better organization:iapService.basic.test.ts: Real method testingiapService.unit.test.ts: Enhanced business logic testsiapService. integration.test.ts: Complex workflow ..

Addressing in OSI Layer 2 and Layer 3 In the OSI 7-layer model, only Layer 2 (Data Link Layer) and Layer 3 (Network Layer) use addressing schemes:Layer 2 uses a physical address, known as the MAC addressLayer 3 uses a logical address, known as the IP addressMAC Address (Layer 2)A MAC address is split into two 24-bit parts:OUI (Organizationally Unique Identifier): Assigned by IEEE to identify th..

PCB (Process Control Block)The Process Control Block (PCB) is a data structure used by the operating system to store *metadata about a process.It is created by the OS when a process is generated.The PCB contains all the essential information needed to manage and control the process.Since it holds critical information, it is protected and maintained at the front of the kernel stack, inaccessible ..

A MAC (Media Access Control) address is a unique identifier assigned to a network interface for communication at the data link layer (Layer 2) of the OSI model. Key Characteristics:It is a physical (hardware) address embedded into the Network Interface Card (NIC) of a device.All devices connected to a network must have a MAC address to participate in communication.The ARP (Address Resolution Pro..

A transaction in a database refers to a unit of work that performs a single logical function,which is a group of multiple queries bundled together.In databases, a transaction is a series of operations or queries that form a single logical unit of work.These operations ensure the database remains consistent by following the ACID properties:AtomicityConsistencyIsolationDurabilityAtomicity (원자성)Ato..

While it is commonly assumed that communication between computers happens through IP addresses, the actual transmission at the data link layer relies on MAC addresses.In reality, IP addresses are used to find corresponding MAC addresses using ARP, and communication is performed based on those MAC addresses.What is ARP?ARP (Address Resolution Protocol) is a network protocol used to map an IP addr..