Answer:
User Datagram Protocol (UDP) , transport-layer segment.
Explanation:
The User Datagram Protocol is popularly known as UDP. It is defined as the communication protocol which is used across the internet for any time sensitive transmission like the DNS lookup or the video playback.
The UDP provides a unreliable and connectionless service to a invoking application.
The transport layers on sending side converts the application 
messages which it 
from the 
into a transport layer segment called as the transport layer segments. This is achieved by breaking down the application messages into a smaller chunks and then adding the transport layer header into each chunk so as to create a transport layer segment.
Answer:
def validateCreditCard(x):
if type(x)==str and len(x) == 8:
print("Valid credit card number")
else:
print("Invalid credit card number")
validateCreditCard("43589795")
Explanation:
Run the code on your text editor(vs code, sublime, pycharm ) you will get your desired response. If your input is not of type string and not up to 8 digit you will get the response "invalid credit card number" but if it is of type string and up to 8 digit you will get "Valid credit card number".
But remember python works with indentation so when you are transferring this code to your text editor it will run properly well.
I defined the code using the conventional pattern "def"
After defining the function you create a brackets (x) to accommodate your argument x and end it with a semi colon.
Then i use "if" statement to make sure only string argument and 8 digit value will be accepted to print a "valid credit card". if your argument does not pass the if statement condition it will print out the else statement condition which is "Invalid credit card number"
Finally, you have to call your function and test various values.
