Computer Networks Fundamentals

Correct Answer: Bus

Star topology requires a central controller or hub that all devices connect to. This central hub manages all communication between connected devices, unlike bus, mesh, or ring topologies.

Transmission media are closest to the physical layer (Layer 1) of the OSI model. The physical layer deals with the actual transmission of raw bits over a physical medium.

GSM (Global System for Mobile Communications) is the cellular telephone system widely used in Europe. AMPS and D-AMPS are primarily American systems, while IS-95 is a CDMA-based system.

Transmission media are categorized as guided (like wires and cables) or unguided (like wireless). Guided media have a physical path, while unguided media transmit through air/vacuum.

IRDA (Infrared Data Association) is the organization that sponsors and develops standards for infrared wave communication. EIA and FCC are regulatory bodies, while PUD is not related to infrared.

LEO satellites typically have polar orbits to maximize global coverage as Earth rotates beneath them. Equatorial orbits are for geostationary satellites, while inclined orbits provide limited coverage.

FTP opens a new data connection for each file transfer operation during a session. The control connection stays open, but data connections are created and closed as needed for each transfer.

The Content-Type field in the MIME header specifies the media type of the message body, such as text/plain or application/json. This tells the recipient how to interpret the data.

POST is the HTTP method used to send data to the server in the request body. Unlike GET (which retrieves data), POST is designed for submitting information to be processed by the server.

The MOVE method is used to move a file to a different location on the server. While not part of standard HTTP/1.1, it is defined in WebDAV (Web Distributed Authoring and Versioning) extensions for file management.

A DNS resolver is the client-side component that initiates DNS queries on behalf of applications. It sends queries to DNS servers and caches responses for future use, acting as the client in the DNS system.

A secondary DNS server obtains its zone data by transferring it from a primary DNS server through zone transfer (AXFR/IXFR). This provides redundancy and load distribution for DNS services.

Address-to-name resolution (reverse DNS) uses the inverse domain (in-addr.arpa). This allows mapping IP addresses back to domain names, which is useful for verification and logging purposes.

With 40 stations on an Ethernet LAN segmented by a 10-port bridge, each segment handles 4 stations (40/10). If the total bandwidth is 10 Mbps and each segment gets 1 Mbps (10/10 ports), then each station in a segment gets 0.25 Mbps (1/4). However, if we calculate based on standard Ethernet collision domain reduction: a 10-port bridge creates 10 collision domains, each with 10 Mbps / 4 stations = 2.5 Mbps effective average per station. The calculation depends on traffic patterns but 2.5 Mbps is a reasonable approximation.

LCP (Link Control Protocol) packets in PPP serve three key purposes: configuration (establishing connection parameters), termination (closing connections), and option negotiation (agreeing on protocol parameters like authentication methods). Option D covers all these functions.

HTTP is an application-layer protocol that shares characteristics with both FTP (File Transfer Protocol) and SMTP (Simple Mail Transfer Protocol). Like FTP, HTTP uses text-based commands and responses. Like SMTP, HTTP has a simple request-response model and uses headers for metadata exchange.

RSA (Rivest-Shamir-Adleman) is a public-key (asymmetric) cryptography algorithm. It uses a pair of keys: a public key for encryption and a private key for decryption. This is different from symmetric cryptography (like AES) which uses the same key for both operations.

In FTP, the control connection is established exactly once at the beginning of the session and remains open throughout. This connection is used for sending commands (like LIST, RETR) and receiving responses. The data connection, by contrast, is opened and closed for each file transfer.