Network+ OSI Model

Which port number is used by HTTPS?

• 443

• 69

• 23

• 80

Windowing is a technology that applies to which transport layer protocol?

• UDP

• TCP

• ICMP

• FTP

Answer explanation

Windowing is one of the technologies that apply to connection-oriented Transmission Control Protocol (TCP) to ensure reliability in communications.

Question :Which setting ultimately controls the size of packets that are moving through the modern network?

• SSH

• MTU

• TTL

• CSMA/CD

Answer explanation

The maximum transmission unit (MTU) is the network interface setting that defines the largest packet that may be sent onto the network.

Which of the following layers of the OSI reference model contains the MAC and LLC sublayers?

• Data link

• Network

• Transport

• Physical

Answer explanation

The data link layer of the open system interconnection (OSI) model is the only layer of the famous model that is divided into sublayers, namely, the media access control (MAC) and logical link control (LLC) sublayers.

Which bandwidth usage approach consumes all the available frequencies on a medium to transmit data?

• Time-division multiplexing

• Simplex

• Broadband

• Baseband

Which of these is a connectionless transport layer protocol?

• UDP

• TCP

• Data link

• ICMP

Answer explanation

User Datagram Protocol (UDP) is a connectionless transport protocol. Connectionless transport protocols offer unreliable transport in that if a segment is dropped, the sender is unaware of the drop, and no retransmission occurs. UDP sacrifices reliability for speed and efficiency in the transport of data.

What happens to data as it moves from the upper layers to the lower layers of the OSI model on a host system?

• The data is sent in groups of segments that require two acknowledgments.

• The header and trailer are stripped off through decapsulation.

• The data is encapsulated with a header at the beginning and a trailer at the end.

• The header and trailer are stripped off through encapsulation.

Answer explanation

As data moves down through the open system interconnection (OSI) model layers (on a host), it is encapsulated with a header added to the beginning and a trailer to the end. When the data arrives at the receiving host, it moves up the model and is decapsulated, in that the header and trailer are stripped off as it moves up through the OSI layers.

Which of these might you want to investigate if you can reach a web server by using its IP address but not its name?

• DNS

• ARP

• NTP

• DHCP

Answer explanation

You might want to investigate domain name server-based (DNS-based) name resolution if you can reach a web server by using its IP address but not its name.

IP addresses reside at which layer of the OSI reference model?

• Transport

• Network

• Session

• Data link

Answer explanation

An IP address resides at the network layer (Layer 3) of the open system interconnection (OSI) model. Routers use these addresses to route traffic through the internetwork.

Which setting ultimately controls the size of packets that are moving through the modern network?

• MTU

• TTL

• CSMA/CD

• SSH

Answer explanation

The maximum transmission unit (MTU) is the network interface setting that defines the largest packet that may be sent onto the network.