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Free Practice Quiz Question List

1 TCP, UDP, and Port Fundamentals Online Quiz Questions

Use this free practice quiz with 20 questions to review 1 TCP, UDP, and Port Fundamentals, test your knowledge, and prepare for your next test or exam.

20 questions
01
Written response
1 point

What is the highest valid port number? Enter an integer.

02
True or false
1 point

A packet addressed to TCP port 22 must be carrying SSH traffic.

  1. A

    True

  2. B

    False

03
Choose one
1 point

A client selects source port 50000 for a temporary connection. Which IANA port range category contains this port?

  1. A

    System (well-known)

  2. B

    Dynamic/private

  3. C

    User (registered)

  4. D

    Outside the valid port range

04
Choose one
1 point

A packet is addressed to destination UDP port 123. Which service is commonly associated with this protocol-and-port pair?

  1. A

    SSH

  2. B

    DHCP

  3. C

    NTP

  4. D

    HTTP

05
Fill in the blank
1 point

For DHCP, the server uses UDP port , and the client uses UDP port .

06
Written response
1 point

What protocol-and-port pair is commonly assigned to SSH?

07
True or false
1 point

TCP provides a reliable, ordered byte stream, retransmitting lost data and acknowledging received data.

  1. A

    True

  2. B

    False

08
Choose all
1 point

Select all statements that correctly describe UDP.

  1. A

    It sends separate datagrams without first establishing a connection.

  2. B

    It guarantees that every message is delivered in order.

  3. C

    It does not itself guarantee delivery or order.

  4. D

    An application can add its own reliability mechanisms.

09
Choose one
1 point

A network analyst sees traffic using UDP port 443. Which interpretation is best supported?

  1. A

    It cannot be HTTP/3 because HTTPS always uses TCP.

  2. B

    It could be HTTP/3 over QUIC, but the port alone does not prove the application.

  3. C

    It must be DNS because UDP port 443 is reserved for DNS.

  4. D

    It must be NTP because all UDP traffic uses port 123.

10
Choose one
1 point

A client at 192.0.2.10 sends a TCP request from source port 53000 to a web server at 203.0.113.20, destination port 443. Which port is the better clue to the intended server service?

  1. A

    Port 53000, because client source ports identify the server service.

  2. B

    Both ports equally, because a client and server must use the same port.

  3. C

    Port 443, because it is the destination port associated with the server service.

  4. D

    Neither port, because TCP does not use port numbers.

11
Fill in the blank
1 point

Together, the source and destination addresses, source and destination ports, and transport distinguish a flow.

12
Choose all
1 point

Select all service-and-port statements that are correct.

  1. A

    HTTP — TCP 80

  2. B

    NTP — UDP 123

  3. C

    DNS — UDP 53 and TCP 53

  4. D

    HTTPS — TCP only

13
Choose one
1 point

A device receives traffic addressed to TCP port 53 and UDP port 53. Why are these not the same transport endpoint?

  1. A

    They are the same endpoint because their port numbers match.

  2. B

    UDP port 53 is invalid because only TCP can use port 53.

  3. C

    They are distinct endpoints because TCP and UDP have separate port spaces.

  4. D

    They must belong to different applications because the transports differ.

14
Open ended
1 point

An application team is choosing a transport for delay-sensitive voice traffic. Compare TCP and UDP for this use case, including their delivery behavior, and explain why neither protocol is universally the better choice.

15
Choose one
1 point

A DHCP server is waiting to receive client requests. Which destination protocol-and-port pair is conventionally used on the server side?

  1. A

    UDP port 67

  2. B

    UDP port 68

  3. C

    TCP port 67

  4. D

    TCP port 68

16
Written response
1 point

In the example flow from 192.0.2.10:53000 to 203.0.113.20:443, what is the client's source port?

17
Choose one
1 point

A packet is addressed to destination TCP port 22. Which conclusion is justified by the port assignment?

  1. A

    The traffic is definitely SSH because TCP port 22 authenticates the application.

  2. B

    TCP port 22 is a clue that the traffic may be SSH, but it does not prove which program is using the port.

  3. C

    TCP port 22 cannot be associated with any service.

  4. D

    The traffic must be a UDP service because port 22 is a system port.

18
True or false
1 point

True or false: HTTPS necessarily uses TCP.

  1. A

    True

  2. B

    False

19
Written response
1 point

A packet is addressed to destination UDP port 123. Which common network service does this port conventionally indicate?

20
Choose one
1 point

An application needs data delivered as a reliable, ordered byte stream, with lost data retransmitted. Which transport protocol fits these requirements?

  1. A

    UDP, because it guarantees ordered delivery without establishing a connection.

  2. B

    TCP, because it provides a reliable, ordered byte stream and retransmits lost data.

  3. C

    UDP, because datagrams are always delivered exactly once.

  4. D

    TCP, because it sends independent datagrams without first establishing a connection.