DISTRIBUTED SYSTEMS-
MIDTEM QUESTIONS WITH
100%VERIFIED ANSWERS
What does the Network Layer do? - ✔✔Routes packets between networks. eg. IP, ATM
What does the Data Link Layer do? - ✔✔Coordinate the transmission between connected
hosts or local area networks. Also collision detection. Eg. Ethernet, MAC
What does the Physical Layer do? - ✔✔Transmit bits over transmission medium. eg. cables
What is packet encapsulation? - ✔✔a technique to pack data packets between layers,
marking where headers and and data starts and ends
What is a router? - ✔✔a device that forwards packets between networks
What are routing algorithms? - ✔✔an algorithm used to determine routes for transmission
packets. Has 2 steps: determine next hop for packet, dynamically update information to other
routers
What is distance vector algorithm? - ✔✔A algorithm used to find best path in network
by each node calculating their next hop costs and propagating that information through it's
neighbors. Each router has a routing table with next hop costs.
What protocol is used to send new next hop information? - ✔✔RIP - router
information protocol
What is the pesudocode for RIP - ✔✔For an incoming routing table, for each row if the link is
not the same as the recv link, then increment the cost by 1 (b/c path uses recv link) and also set
link start to next hop recv link. If destination not in current table, add new path. Else loop
through current table and update based on lower cost and if new information(cur_table_rows.link
== recv link)
, What is UDP? - ✔✔Stands for user datagram protocol. It's connectionless
communication. Each message is encapsulated into a packet called datagram. No guarantee
order
What is TCP? - ✔✔Stands for transmission communication protocol. It's provides:
connection-oriented communication (Sessions), reliability, and congestion control.
What is connection-oriented communication? - ✔✔Two features:
Sender and reciever will handshake to setup connection,
Provides in order transmission of data.
How does TCP be reliable? - ✔✔Each requests waits for ACK from receiver if no ACK,
send packet again
How is congestion control handled? - ✔✔If router detects congestion, sends out a
explicited congestion notificaiton (ECN) and senders should lower TCP packets rate
What is packet switching? - ✔✔User divides their data into small chunks called packets to
get sent over the network.
What are the two main architectures of distributed systems - ✔✔Master/slave and Peer to peer
What characteristics make a master/slave architecture? - ✔✔- nodes are unequal ( hierarchy)
- master acts as a central coordinator
- underlying systems cannot scale out indefinitley (bottlenecked by master)
What characteristics make a peer 2 peer architecture? - ✔✔- all nodes are equal
- a central coordinator is not needed
- underlying system can scale out indefinitely
MIDTEM QUESTIONS WITH
100%VERIFIED ANSWERS
What does the Network Layer do? - ✔✔Routes packets between networks. eg. IP, ATM
What does the Data Link Layer do? - ✔✔Coordinate the transmission between connected
hosts or local area networks. Also collision detection. Eg. Ethernet, MAC
What does the Physical Layer do? - ✔✔Transmit bits over transmission medium. eg. cables
What is packet encapsulation? - ✔✔a technique to pack data packets between layers,
marking where headers and and data starts and ends
What is a router? - ✔✔a device that forwards packets between networks
What are routing algorithms? - ✔✔an algorithm used to determine routes for transmission
packets. Has 2 steps: determine next hop for packet, dynamically update information to other
routers
What is distance vector algorithm? - ✔✔A algorithm used to find best path in network
by each node calculating their next hop costs and propagating that information through it's
neighbors. Each router has a routing table with next hop costs.
What protocol is used to send new next hop information? - ✔✔RIP - router
information protocol
What is the pesudocode for RIP - ✔✔For an incoming routing table, for each row if the link is
not the same as the recv link, then increment the cost by 1 (b/c path uses recv link) and also set
link start to next hop recv link. If destination not in current table, add new path. Else loop
through current table and update based on lower cost and if new information(cur_table_rows.link
== recv link)
, What is UDP? - ✔✔Stands for user datagram protocol. It's connectionless
communication. Each message is encapsulated into a packet called datagram. No guarantee
order
What is TCP? - ✔✔Stands for transmission communication protocol. It's provides:
connection-oriented communication (Sessions), reliability, and congestion control.
What is connection-oriented communication? - ✔✔Two features:
Sender and reciever will handshake to setup connection,
Provides in order transmission of data.
How does TCP be reliable? - ✔✔Each requests waits for ACK from receiver if no ACK,
send packet again
How is congestion control handled? - ✔✔If router detects congestion, sends out a
explicited congestion notificaiton (ECN) and senders should lower TCP packets rate
What is packet switching? - ✔✔User divides their data into small chunks called packets to
get sent over the network.
What are the two main architectures of distributed systems - ✔✔Master/slave and Peer to peer
What characteristics make a master/slave architecture? - ✔✔- nodes are unequal ( hierarchy)
- master acts as a central coordinator
- underlying systems cannot scale out indefinitley (bottlenecked by master)
What characteristics make a peer 2 peer architecture? - ✔✔- all nodes are equal
- a central coordinator is not needed
- underlying system can scale out indefinitely
