Real QnA

[Plasma_Snake]

Well we can get our Engg notes and lectures through NPTEL but is there any site where we can post our questions and get answers if not instantly then after few hours or so, like "Why Data Link Protocol always puts CRC in Header rather than in trailer?"

ya i was thinking to make one site like that

[jal_desai]

asfar as i remember the basics of Computer Networks, the CRC is the cyclic redundancy check... it must be the same when delivering and receiving ends... if it is not, then the packet is believed to have lost some data in the "unreliable medium"... the packet is considered useless. this has to be done prior to reading any data from the packet... and tht's y the header contains CRC along with destination address and other data...

[Kl@w-24]

The header is the portion that's processed first. So if a packet has an invalid CRC, there's no need to perform any further processing on that packet. If the CRC was in the trailer, the host would have to store the entire packet in its buffer, then calculate and check the CRC found in the trailer, thereby wasting precious processing time.

[Plasma_Snake]

Whew! With such quick responses I don't think there's need for any other site. Digit Forum Rocks the Ballz out!

BTW Abh1shek CRC is checked upon recieving against the data recieved, so data is needed to be processed in either case to check the calculated CRC against the one provided in the header so the reason for doing so still remains elusive to me. Tell ya'll when find the answer by tomorrow. (Computer Networks Exam tomorrow)

[Plasma_Snake]

Well today I had my Computer Networks Exam and was it STUPID. Checkout the question paper itself.
http://1zspmg.bay.livefilestore.com/...Dg/CN_Qppr.jpg
http://1zspmg.bay.livefilestore.com/...Q/CN_Qppr2.jpg

I mean how can they ask 3rd Year I.T Engg.students such stupid questions? i nailed it as expected but I was expecting question to a bit tough based on previous year question papers like Routing Algorithms and solving numerical problems using 2-D Parity Check,Hamming Distance and CRC.
Anyway the question that I asked earlier, still is elusive and will like someone to answer it before I do it myself.