Quiz 5 Flashcards
(31 cards)
What is the basic operation of a switch?
A switch forwards frames based on MAC addresses by looking them up in a forwarding table.
How does a switch differ from hubs and repeaters?
Hubs and repeaters operate at Layer 1 and forward all signals blindly; switches operate at Layer 2 and forward selectively using MAC addresses.
What is the difference between full-duplex and half-duplex communication?
Full-duplex allows simultaneous sending and receiving; half-duplex allows only one direction at a time.
Why are switched networks more efficient than shared media networks?
They eliminate collisions
How does the backward learning algorithm work in switches?
The switch learns which MAC addresses are reachable via which ports by observing the source address of incoming frames.
What is the problem of forwarding loops in switched networks?
Frames can circulate endlessly
How does the Spanning Tree Protocol prevent loops?
It disables certain ports to create a loop-free logical topology while maintaining overall connectivity.
What are the steps of the Spanning Tree Algorithm?
- Root Election: The switch with the lowest identifier (bridge ID) is elected as the root of the spanning tree
- Path Selection: Each non-root switch selects a single port to forward frames toward the root (its root port)
- Designated Ports: For each network segment, one port is selected as the designated port to forward frames away from
the root - Blocking: All other ports are put in blocking state and do not forward frames
What is the purpose of VLANs?
VLANs divide a physical network into logical segments to reduce broadcast domains and increase manageability.
How does VLAN tagging work?
A VLAN tag is inserted into Ethernet frames to identify their VLAN; switches use this tag for forwarding decisions.
What are the benefits of VLANs?
Improved security
What are some limitations of switches?
Limited scalability
What are the key limitations of the network layer that the transport layer addresses?
No guarantees of delivery
What does it mean that TCP is a byte-oriented protocol?
TCP assigns sequence numbers to individual bytes
How does TCP use sequence numbers?
Each byte in the stream is numbered; segments carry the sequence number of the first byte they contain.
How does TCP use acknowledgment numbers?
The ACK number indicates the next expected byte
How can you calculate the sequence number for a TCP segment?
It equals the number of the first byte of data in that segment.
How can you calculate the acknowledgment number for a TCP segment?
It is one more than the last byte successfully received.
What is the purpose of the Source and Destination Port fields in the TCP header?
To identify the sending and receiving applications.
What is the purpose of the Window Size field in the TCP header?
It indicates how much data the receiver is willing to accept
What does the Checksum field in the TCP header do?
It helps detect transmission errors.
What are the six TCP control flags?
- SYN (Synchronize): Initiates a connection
- ACK (Acknowledgment): Acknowledges received data
- FIN (Finish): Initiates the connection termination
- RST (Reset): Abruptly terminates the connection
- PSH (Push): Pushes data to the application without buffering
- URG (Urgent): Indicates urgent data
What is the function of the SYN flag?
Initiates a TCP connection.
What is the function of the ACK flag?
Acknowledges received data.
