1.2b - Networking Functions

Vocabulary flashcards covering key networking functions including protocols, traffic management, and loop prevention mechanisms.

CDN (Content Delivery Network)

A network of servers designed to provide data efficiently from a central point to an end user by caching information at various geographical points around the world.

VPN (Virtual Private Network)

A method that allows a user to connect to a remote network securely by encrypting all data sent across potentially insecure networks like the public internet.

VPN Concentrator

A purpose-built appliance or head-end device designed to handle high-speed encryption and decryption for many simultaneous VPN users.

QoS (Quality of Service)

A network configuration, also known as traffic shaping or packet shaping, used to prioritize specific applications or traffic types, such as real-time audio or video, over others.

Time to Live (TTL)

A mechanism used to prevent tasks or packets from running indefinitely on a network, often implemented as a timer or a counter of iterations.

Routing Loop

A networking error where a packet is passed back and forth between routers (e.g., Router A to Router B and back) without reaching its destination, often caused by a mistake in a static route.

IP Time to Live (TTL)

A field in the $IPv4$ header that specifies the number of hops a packet is allowed to take; each router reduces this value by one and discards the packet if it reaches zero.

MacOS/Linux Default TTL

The default number of hops set for outgoing packets on these operating systems, which is usually $64$ hops.

Windows Default TTL

The default number of hops set for outgoing packets on this operating system, which is usually $128$ hops.

DNS Time to Live (TTL)

A value in the Domain Name System, measured in seconds, that determines how long a local system should cache a DNS resolution entry before performing a new lookup.

dig

A command-line tool used for performing DNS lookups to retrieve information such as IP addresses and TTL values associated with a domain.