Networking Models and Protocols Flashcards

What does the acronym 'PDU' stand for in networking?

Answer: Protocol Data Unit

PDU stands for Protocol Data Unit, the generic term for data at each OSI layer (e.g., segment at Transport, packet at Network, frame at Data Link).

Which protocol is used to automatically assign IP addresses to devices on a network?

Answer: DHCP

DHCP (Dynamic Host Configuration Protocol) automatically assigns IP addresses, subnet masks, default gateways, and DNS server addresses to clients.

The three-way handshake used by TCP involves which sequence of messages?

Answer: SYN → SYN-ACK → ACK

TCP establishes a connection with SYN from client, SYN-ACK from server, then ACK from client — a three-way handshake.

Which OSI layer adds a MAC address header to data, creating a frame?

Answer: Data Link layer

The Data Link layer (Layer 2) encapsulates packets into frames and adds source and destination MAC addresses.

In IPv4, what is the purpose of the subnet mask?

Answer: To identify the network and host portions of an IP address

A subnet mask distinguishes the network portion from the host portion of an IPv4 address, enabling proper routing decisions.

Which protocol resolves IP addresses to MAC addresses on a local network segment?

Answer: ARP

ARP (Address Resolution Protocol) broadcasts a request on the local segment to discover the MAC address associated with a known IP address.

A user can ping a server by IP address but not by hostname. Which protocol is most likely failing?

Answer: DNS

DNS (Domain Name System) resolves hostnames to IP addresses; if ping by IP works but hostname fails, DNS resolution is the issue.