Knowledge in Computer Networks
Linked List-Reference
One disadvantage of using arrays to store data is that arrays are static structures and therefore cannot be easily extended or reduced to fit the data set. Arrays are also expensive to maintain new insertions and deletions. In this chapter we consider another data structure called Linked Lists that addresses some of the limitations of arrays. A linked list is a linear data structure where each element is a separate object. Each element (we will call it a node) of a list is comprising of two items - the data and a reference to the next node. The last node has a reference to null. The entry point into a linked list is called the head of the list. It should be noted that head is not a separate node, but the reference to the first node. If the list is empty then the head is a null reference. A linked list is a dynamic data structure. The number of nodes in a list is not fixed and can grow and shrink on demand. Any application which has to deal with an unknown number of objects will need to use a linked list. One disadvantage of a linked list against an array is that it does not allow direct access to the individual elements. If you want to access a particular item then you have to start at the head and follow the references until you get to that item. Another disadvantage is that a linked list uses more memory compare with an array - we extra 4 bytes (on 32-bit CPU) to store a reference to the next node.
Abir Biswas
Finite Automata
Definition of Finite Automata. A finite automaton (FA) is a simple idealized machine used to recognize patterns within input taken from some character set (or alphabet) C. The job of an FA is to accept or reject an input depending on whether the pattern defined by the FA occurs in the input. In the theory of computation, a branch of theoretical computer science, a deterministic finite automaton —also known as deterministic finite acceptor, deterministic finite state machine
Regular Expressions
A regular expression, regex or regexp is a sequence of characters that define a search pattern. Usually such patterns are used by string searching algorithms for "find" or "find and replace" operations on strings, or for input validation
Linear Modulation
It is a modulation technique for which super- position theorem stands correct. The modulations for which the above theorem does not hold good are called non-linear modulations. Linear modulation is the direct frequency translation of the message spectrum. DSB modulation (Double sideband) is precisely that.
Angle Modulation
Angle modulation is a class of carrier modulation that is used in telecommunications transmission systems. The class comprises frequency modulation (FM) and phase modulation (PM), and is based on altering the frequency or the phase, respectively, of a carrier signal to encode the message signal.
Digital Transmission of Analog Signals
To transmit analog message signals, such as voice and video signals, by digital means, the signal has to be converted to a digital signal. This process is known as the analog-to-digital conversion, or sometimes referred as digital pulse modulation.
Insertion Sort
Insertion sort is a simple sorting algorithm that builds the final sorted array one item at a time. It is much less efficient on large lists than more advanced algorithms such as quicksort, heapsort, or merge sort.
Asymptotic Notation
Asymptotic Notations are languages that allow us to analyze an algorithm's running time by identifying its behavior as the input size for the algorithm increases. This is also known as an algorithm's growth rate.
Dynamic Programming
Dynamic Programming is mainly an optimization over plain recursion. Wherever we see a recursive solution that has repeated calls for same inputs, we can optimize it using Dynamic Programming. The idea is to simply store the results of subproblems, so that we do not have to re-compute them when needed later.
ISO-OSI 7-Layer Network Architecture
The International Standards Organization (ISO) developed the Open Systems Interconnection (OSI) model. It divides network communication into seven layers. ... Layers 5-7, called the the upper layers, contain application-level data. Networks operate on one basic principle: "pass it on."
DNS, BOOTP, DHCP
BOOTP is implemented using the User Datagram Protocol (UDP) as transport protocol, port number 67 is used by the (DHCP) server to receive client requests and port number 68 is used by the client to receive (DHCP) server responses. BOOTP operates only on IPv4 networks.
Network Security
Network security is any activity designed to protect the usability and integrity of your network and data. It includes both hardware and software technologies. Effective network security manages access to the network. It targets a variety of threats and stops them from entering or spreading on your network.