Computer Networks

A modem is used to connect to a Wide Area Network (WAN) or the internet, typically via telephone or cable lines. Local Area Networks (LANs) typically use switches, hubs, or routers for internal connectivity.

Mesh topology provides highest reliability.

A baseband signal is the original, un-modulated signal generated by a source before it is shifted to a higher frequency range for transmission. Modulation is the process of superimposing this signal onto a carrier.

The local loop, or the last mile connection between a subscriber and the central office, has historically and predominantly used copper twisted pair wiring for telephone services.

A mesh topology is characterized by connections between nodes where every node may be connected to every other node, allowing for multiple paths and bi-directional communication.

The size of next generation IP address (IPv6) is 16 bytes (128 bits).

ARP maintains a cache or lookup table that maps known IP addresses to their corresponding physical MAC addresses on a local network segment.

In asynchronous serial communication, start and stop bits are used to frame the data, allowing the receiver to identify the beginning and end of each character for proper synchronization.

HDLC (High-Level Data Link Control) is a bit-oriented protocol, meaning it treats data as a stream of bits rather than specific character codes, allowing for any arbitrary bit pattern.

An IP address consists of four octets. Each octet is 8 bits, allowing for values ranging from 0 (binary 00000000) to 255 (binary 11111111).

An example of full duplex transmission is telnet.

FTP is the standard network protocol used for the transfer of computer files between a client and server on a computer network.

ARPANET was one of the first networks to implement dynamic routing, where the path taken by packets could change based on network conditions.

Cyclic Redundancy Check (CRC) is a common error-detecting code used in digital networks and storage devices to detect accidental changes to raw data.

An Ethernet frame includes fields for destination and source addresses, type/length, and data, but it does not contain a 'pin code' field.

FTP, SMTP, and HTTP are all application-layer protocols that rely on the Internet Protocol (IP) for transport and routing of their data packets.

 Internet is evolved from ARPANET.

Baud rate refers to the number of signal units (symbols) transmitted per second. It is distinct from bit rate, which measures the number of bits per second.

Twisted pair, fibre optic, and coaxial cable are all guided transmission media (physical cables). Microwave is an unguided transmission medium (wireless).

Bit stuffing is used in protocols like HDLC to ensure that a specific flag sequence (e.g., 01111110) does not appear within the actual data payload, preventing the receiver from misinterpreting the end of a frame.

The OSI (Open Systems Interconnection) reference model is defined by seven distinct layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

Telephone lines transmit data one bit at a time over a single channel, which is the definition of serial transmission.

Full duplex communication allows data to be sent and received simultaneously, unlike half-duplex (one at a time) or simplex (one direction only).

The Internet Protocol (IP) operates at the Network layer (Layer 3) of the OSI model, where it handles logical addressing and routing of packets.