An opcode (operation code) is the portion of a machine language instruction that specifies the operation to be performed.

Telnet is an application layer protocol.

The Spanning Tree Protocol (STP) is a network protocol that ensures a loop-free topology for any bridged Ethernet local area network. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include spare (redundant) links to provide automatic backup paths if an active link fails, without the danger of bridge loops or the need for manual enabling/disabling of these backup links.

A feasibility study is the evaluation and analysis of  potential of a proposed project, which is based on extensive investigation and research to support the process of decision making. It is the first phase of Software Development Life Cycle (SDLC).

In Optimal Page Replacement Policy, when a page needs to be swapped in, the operating system swaps out the page whose next use will occur farthest in the future.

C is a context-free language.

Swap space is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.

First In First Out (FIFO) is the simplest scheduling algorithm. FIFO simply queues processes in the order that they arrive in the ready queue.

The Constructive Cost Model (COCOMO Model) is an algorithmic model used for software cost estimation. 

A stack is a particular kind of abstract data type or collection in which the principal (or only) operations on the collection are the addition of an entity to the collection, known as push and removal of an entity, known as pop. The relation between the push and pop operations is such that the stack is a Last-In-First-Out (LIFO) data structure. It is the best data for checking the balancing of parenthesis.

 Insertion sort is a simple sorting algorithm that builds the final sorted array (or list) one item at a time. It is a sequential technique.

UDP uses a simple transmission model with a minimum of protocol mechanism. It has no handshaking dialogues and thus exposes any unreliability of the underlying network protocol to the user's program.

Writing the microcode is often called microprogramming and the microcode in a particular processor implementation is sometimes called a microprogram. Microprogramming is the designing of the CPU.

 Kernel threads do not own resources except for a stack, a copy of the registers including the program counter and thread-local storage

The Reverse Address Resolution Protocol (RARP) is a computer networking protocol used by a host computer to request its Internet Protocol (IPv4) address from an administrative host, when it has its Link Layer or hardware address available, such as a MAC address.