Trouble differentiating TCP and UDP Ports

Vask3n

Hi everyone, I have trouble whenever I come across a question on a practice exam asking for a port number, and the answers contain options such as:
TCP Port 25
TCP and UDP Port 25
UDP Port 25
(Just an example)

Does the actual exam expect you to differentiate between TCP and UDP Ports? I've memorized most of the TCPs, but if I have to go through the UDPs as well, I'm toast.

sprkymrk

As far as I can tell, yes. But the good news is that MOST of the time you can assume TCP (if you have to guess). The main UDP stuff I would make sure you know are UDP 53 for dns, know what kind of attack a UDP flood is, and remember that fraggle is a UDP variant of the smurf attack (using udp port 7 echo packets instead of ICMP). That's off the top of my head, I'm probably missing a couple. I'm not sure if they ask about stuff like port numbers for VPN's (esp is udp 500 etc.).

Maybe someone else can enlighten us?

bcairns

The ports that they are focused on are called "well known ports" port 0 to 1023

Most of this ports relate to services - the service defines if TCP or UDP is used.

SMTP = TCP 25
POP3 = TCP 110
TFTP = UDP 69
... etc etc

keatron

If you check out the ports list here in the technotes.

Also look at the ports section of the Network+ practice exams.

Danman32

Consider the different nature and purpose for UDP and TCP. UDP is used more for short bursty messages that may or may not need a reply, and if a reply is required, it is better to just resubmit the message if a reply is not received in a specific time period.

TCP however initiates a two way conversation with acknowlegements and flow control. It will be more commonly used for fairly lengthy dialog.

sprkymrk

Danman32 wrote:

Consider the different nature and purpose for UDP and TCP. UDP is used more for short bursty messages that may or may not need a reply, and if a reply is required, it is better to just resubmit the message if a reply is not received in a specific time period.

TCP however initiates a two way conversation with acknowlegements and flow control. It will be more commonly used for fairly lengthy dialog.

UDP can be used for any size communications where it would be undesireable to retransmit lost packets, such as streaming audio or video. Yet we all know that these files can be quite large and long. One of the main things is speed, UDP is faster because it does not require acknowledgments. It shoots the packets and doesn't care if you get them all or not.