BSCI Exam Guide Test Software Errata

Hey Guys,

Two questions:

1. Does anybody know if there is an errata listing for the questions contained in the cisco press exam test engines that come with the official exam guides?

2. There is an EIGRP question on the CCNP BSCI practice exam test software that asks:

"Which of the following describes how a reply to an EIGRP query is sent?"

a. A reliable unicast
b. A reliable multicast
c. Best effort unicast
d. Multicast

The exam engine says that C is the correct answer but i would argue that A is the correct answer. My logic is that a reply to a query does requir a coresponding ack so it is therefore reliable.

However, if by "reply" this question was refering to the "ack" then answer c would be correct. What do you guys think?

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Comments

networker050184

Funny, I did those questions last night. My answer was C for the reason you gave for C also.

jason_lunde

Internetworking Technology Handbook - Enhanced Interior Gateway Routing Protocol (EIGRP) [Internetworking] - Cisco Systems

"Query and reply packets are sent when a destination has no feasible successors. Query packets are always multicast. Reply packets are sent in response to query packets to instruct the originator not to recompute the route because feasible successors exist. Reply packets are unicast to the originator of the query. Both query and reply packets are transmitted reliably. "

So A would seem to be the best answer...would be nice to see any errata if there is any.

\\\<I see a debug eigrp packet in my future tonight>///

malcybood

I'd say the answer is A

Going on the basis that everything I've read states that the only packets that do not require a reliable unicast reply are hello's and ack's in EIGRP.

networker050184

malcybood wrote: »

I'd say the answer is A

Going on the basis that everything I've read states that the only packets that do not require a reliable unicast reply are hello's and ack's in EIGRP.

Exactly the reply to a Query is first an ACK then the Reply comes. So the real question is what is the question asking? Not worded very well IMO.

networker050184

Here is a quick debug

*Jul 15 16:35:18.611: EIGRP: Received QUERY on Serial1/0.1 nbr 10.0.0.2
*Jul 15 16:35:18.611:   AS 100, Flags 0x0, Seq 3/2 idbQ 0/0 iidbQ un/rely 0/0 pe
erQ un/rely 0/0
*Jul 15 16:35:18.615: EIGRP: Enqueueing ACK on Serial1/0.1 nbr 10.0.0.2
*Jul 15 16:35:18.615:   Ack seq 3 iidbQ un/rely 0/0 peerQ un/rely 1/0
*Jul 15 16:35:18.623: EIGRP: Sending ACK on Serial1/0.1 nbr 10.0.0.2
*Jul 15 16:35:18.627:   AS 100, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ un/rely 0/0 pe
erQ un/rely 1/0
*Jul 15 16:35:18.631: EIGRP: Enqueueing REPLY on Serial1/0.1 nbr 10.0.0.2 iidbQ
un/rely 0/1 peerQ un/rely 0/0 serno 3-5
*Jul 15 16:35:18.639: EIGRP: Sending REPLY on Serial1/0.1 nbr 10.0.0.2
R1#
*Jul 15 16:35:18.643:   AS 100, Flags 0x0, Seq 3/3 idbQ 0/0 iidbQ un/rely 0/0 pe
erQ un/rely 0/1 serno 3-5
*Jul 15 16:35:18.727: EIGRP: Received ACK on Serial1/0.1 nbr 10.0.0.2
*Jul 15 16:35:18.727:   AS 100, Flags 0x0, Seq 0/3 idbQ 0/0 iidbQ un/rely 0/0 pe
erQ un/rely 0/1

So, as you can see the ACK is sent in response to the Query.

malcybood

If this was a Cisco exam I think the key to what the question was asking would be in the word reply.

"Which of the following describes how a reply to an EIGRP query is sent?"

a. A reliable unicast
b. A reliable multicast
c. Best effort unicast
d. Multicast

If it was referring to an ack I think the question would just say.

"Which of the following describes how an ack to an EIGRP query is sent?"

a. A reliable unicast
b. A reliable multicast
c. Best effort unicast
d. Multicast

This is the sort of thing Cisco put in to test your attention to detail in my experience, but when you re-read the question it is usually clear what they're asking. Who knows with Ciscopress questions though.

jason_lunde

Right, I think we all agree on the sequence of

query (reliable)
ack (non-reliable)
reply (reliable)
ack (non-reliable)

I agree with malcy that the wording is just jacked up in that question. There have been alot of questions posted on EIGRP packets lately!

networker050184

I think the issue is that a packet shouldn't be called a reply

But I still stick to answer C as being correct. The reply to a query is an ack and that is sent unreliable.

Forsaken_GA

Yeah, the author of that book seems to have committed one of the cardinal sins. I agree that with most things, you'd equate Reply and Ack in reliable communications, but it makes your brain hurt with EIGRP since there is a packet type specifically called Reply and it has a purpose that isn't acknowledging receipt of packets.

So I'd go with C as the answer to the question, as I believe the author intended ACK instead of Reply

adam-b

thanks for the thoughts guys!

Cyanic

You can almost guarantee that this question would not make it to the exam worded this way. The exam questions are scrutinized more thoroughly then what makes it in the books and study materials. I have personally talked with a couple of the question writers at Networkers and they assured me that do not trick the examinees with plays on words.