TestKing question

yes, UDP has no sequence field in its header. This may not be the case for other L4 protocols such as RTP (often used for VoIP) - they may have been thinking of this.

It's more common to lose packets than to get a lot out of order. In this scenario, it seems to me there's a good possibility they are using a routing protocol that supports load sharing (RIP or IGRP).

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Iam learning to CCNA exam (648-801) from TestKing

Below is question, and i consider that a right answer is B but TestKing suppose that is a C, what do You think about that ?

The corporate head office of TestKing has a teleconferencing system that uses a VOIP (voice over IP) system that uses UDP datagrams to send and receive voice data. If for whatever reason the network connection is compromised, what would happen if the datagrams would arrive to their destination out of sequence?

A. UDP will send an ICMP Information Request to the source host.

B. UDP will pass the information in the datagrams up to the next OSI layer in the order that they arrive.

C. UDP will drop the datagrams.

D. UDP will use the sequence numbers in the datagram headers to reassemble the data in the correct order.

E. UDP will not acknowledge the datagrams and wait for a retransmission of the datagrams.

In my opinion UDP doesnt know that received a segment out of sequence, because UDP segments hasn't any field in header with sequence number or something similary, so UDP pass this segment to upper layers and them should have a detecet error mechanism.

Reply to
Piotr Witkowski

Test king gets my vote.

Reply to
Steve C


I agree with Piotr (czesc 8) )

UDP would have no basis upon which to decide to drop the packet. There's no sequencing so the packets would just be passed along on a per packet basis.

"Steve C" wrote in news:M8QXd.98$ snipped-for-privacy@newsread3.news.atl.earthlink.net:

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I would say that B is the right answer. Out-of-sequence is also part of the QoS problems with VoIP.

They also talk specifically about UDP and not about RTP. RTP would be the next higher layer OSI protocol. If RTP has any sequence numbers it's RTS's job to deal with it, not UDP.

As for testking, don't believe them more as far as you can throw a rock at them. I guess the only reason Cisco doesn't sue them is because a lot of answers are incorrect. The quality really sucks and it's not worth the 60-or-so bucks you have to pay for it.

Better get a decent book and use your own healthy reasoning. This will also make sure you pass the exam.


Reply to
Danny Muizebelt

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