CCNA - Practice Test Ques.

Author

Practice Test Ques.

HellaSkillz

2002-10-19, 1:59 pm

Ok, here's another practice test question that I think may be wrong...

Does data always arrive in the order it was sent in the data transfer stage?

A. Yes
B. No

Their answer is... A(yes).

I thought the answer was B(no), because data can take different paths, packets can be dropped or destroyed and need to be resent, and thats what the sequence field in the header is for(so the data can be put in the proper order at the recieving station. But then again, what do I know?

Any input would be sweet!
Thanx

mindmesh

2002-10-20, 9:00 am

I agree with you. Probably a typo. Unless I'm mistaken, but I'm just starting cisco ..

twister166

2002-10-20, 8:02 pm

If it is reliable transport then yes, if not then no. In another word if TCP yes, and UDP no.

kphua

2002-10-21, 5:30 am

Mmm...I don't quite agree with the saying that if you use TCP then packets will always arrive in order, and if you use UDP then they won't.

The idea behind "reliable transport" in TCP is that each and every packet is sequenced, so that even if a packet arrives in the wrong sequence, the upper layers (i.e. the Application layers) can make use of the sequence number to re-organize the packets in the proper order. That does not mean, however, that packets will always arrive in order.

In short, packets can arrive out of order, regardless of whether you're using TCP or UDP. The difference between TCP and UDP is that TCP packets are sequenced to give an impression of "reliable transport", and UDP packets are not.

Either way, it's a badly-worded question anyways

quote:
Originally posted by twister166
If it is reliable transport then yes, if not then no. In another word if TCP yes, and UDP no.

HellaSkillz

2002-10-23, 4:30 pm

yes it is, thanx guys

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