CPEN 247 Final Exam - Gonzaga University

Forwarding moves packets from a router's input to the appropriate output (Data Plane), while routing determines the entire route taken from source to destination (Control Plane)

Packet switching breaks data into chunks and shares resources on demand, while circuit switching reserves netweork resources (like link rates and bufferes) for the entire duration of the communication

Application, Transport, Network, Link, and Physical

A network entity with disk storage that serves HTTP requests on behalf of the origin web server to reduce response time and traffic load

POP handles authorization, downloading and deletion of messages, while IMAP allows users to create folders, move messages, and search remote folders

It Checks the freshness of the cached object by including an If-Modified-Since header in the request

The ACK number represents the sequence number of the nest byte the reciver is expecting, implicitly acknowledging all previous bytes

Flow control prevents the sender from overwhelming the receiver's available buffer space, while congestion control prevents the sender from overwhelming the network's router buffers

The receipt o fthree duplicate ACKs for the same data.

LS is centalized and uses Dijkstra's algorithm where all routers know the complete network topology, whereas DV is decentralized and uses the Bellman-Ford equation where routers only communicate with their physicall connected neighbors

OSPF is an intra-AS routing protocol (routing within an Autonomous System), while BGP is an inter-AS routing protocol (routing between different Autonomous Systems).

The Internet Control Message Protocol is used by hosts and routers to communicate network-layer information, such as error reporting and echo requests (used by ping and traceroute)

Carrier Sense Multiple Access with Collision Detection; a random access protocol where a node listens before speaking, and stops transmitting if it detects a collision

Through self-learning; whenever a frame is received, the switch records the source MAC address and the incoming interface in its switching table

The Address Resolution Protocol translates IP addresses to MAC addresses for communication within a Local Area Network(LAN)

The internet consists of the network edge (hosts/end systems like clients and servers) and the network core (the mesh of packet switches and links).

End systems connect via DSL, cable modems, enterprise Ethernet, or wireless access (WiFi/Cellular)

The internet was originally designed without heavy security; today it is vulnerable to malware (viruses/worms), DoS (Denial of Service) attacks, packet sniffing, and IP spoofing.

Applications operate either on a Client-Server model (where the server is always on with a permanent IP) or a Peer-to-Peer (P2P) model (where peers directly communicate and self-scale)

Processes communicate through a socket (API), which acts as the interface between the application and the transport layer.

Hypertext Transfer Protocol uses TCP port 80. It is stateless but uses cookies to track user sessions.

Relies on SMTP (TCP port 25) to push messages between servers reliably, and protocols like POP3 or IMAP for clients to pull messages to their user agents.

TCP requires a 3-way handshake to establish a logical, full-duplex, point-to-point connection.

TCP guarantees delivery without errors, gaps, or duplicates using sequence numbers, ACKs, and timeout retransmissions.

The congestion window (cwnd) increases exponentially (doubles every RTT) until a loss occurs or a threshold is reached.

cwnd increases linearly (by 1 MSS per RTT).

Initiated upon receiving 3 duplicate ACKs, cutting cwnd in half instead of restarting from 1 MSS.

Computes the least-cost paths using a complete topology map. Message complexity is O(nE).

Nodes maintain distance estimates and update them asynchronously when neighbors share new info. Susceptible to "count-to-infinity" routing loops.

To solve scalability issues, routers are grouped into ASes. Intra-AS routing uses protocols like OSPF, while Inter-AS routing uses BGP.

(Simple Network Managment Protocol) allows mangaging servers to control network devices using a request-response model.

Responsible for framing datagrams, link access (MAC), and error detection(CRC)

TDMA (Time Division) and FDMA (Frequency Division) divide the channel equally but leave unused slots idle.

ALOHA and CSMA allow random transmissions but suffer from collusions.

Polling and Token-Passing eliminate collisions but introduce overhead and single points of failure.

Ethernet is unreliable, connectionless, and uses CSMA/CD. Switces are transparent, plug-and-play devices that filter and forward frames without needing IP configurations.

An intra-AS routing protocol used fro routing traffic within a single Autonomouse System.

An inter-AS routing protocol used for routing traffic between different Autonomouse Systems

An application-layer protocol that pushes emaail messages between servers reliably, operating on TCP port 25

The basic transfer units (packets) of data in a network; the link layer is specifically responsible for framing these datagrams for physical transmission.

A sublayer of the link layer responsible for link access. Thing Adresses are physical hardware identifiers used to route frames withing a Local Area Network(LAN)

An error-detection code used at the link layer to check transmitted frames for accidentall changes to raw data.

It is a random access protocol where a node "listens" to the channel before speaking, and immediately stops transmitting if it detects a data collision