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Quiz and Snack

Quiz and Snack. ECS 152B Winter 2006. Multimedia Two. Describe an FEC scheme. A three-minute MP3 song occupies how much disk space? Between 1MB to 10MB. Mean compensation for computer-industry professional

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Quiz and Snack

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  1. Quiz and Snack ECS 152B Winter 2006

  2. Multimedia Two • Describe an FEC scheme. • A three-minute MP3 song occupies how much disk space? • Between 1MB to 10MB. • Mean compensation for computer-industry professional • The January 2006 IT Salary Survey reveals that the mean compensation for computer-industry professionals rose to $74,636 in the last quarter of 2005, slightly up from $69,579 during the final quarter of 2004.

  3. TCP quiz 1 • Pipelining is used in • Multimedia streaming, persistent HTTP, TCP • The RTT between Davis and D.C. is about • 48ms without queueing delay • The chancellor & Provost of UC Davis • Larry Vanderhoef and Virginia Hinshaw

  4. TCP quiz 2 • Why does the seq. # in TCP count byte while the seq. # in RTP counts packets? Can we reverse them? • Does UDP perform flow control?

  5. TCP Quiz • TCP connection establishment SYN= ? , client_ISN=1234 SYN= ? , server_ISN=4321, Ack=? SYN= ? , seq#=? , ack=?

  6. TCP Quiz • A TCP flow with short RTT, a TCP flow with long RTT. They share the link of the sender. Which one gets a higher transmission rate? Then consider a TCP flow with short RTT and a UDP flow with long RTT. • What are the fields in TCP header? Which fields are the same as UDP?

  7. TCP throughput • After three duplicate Acks, a congestion avoidance algorithm reduces its congestion window to cwnd/3. What is the average throughput using this algorithm? • Linearly increasing from W/3 to W. Thus, average is 2/3*W/RTT. This TCP is more aggressive.

  8. Congestion Control • TCP does AIMD. Can we do MIAD; i.e., to increase multiplicatively and decrease linearly?

  9. IP Quiz • What fields in an IP datagram can be changed in an intermediate router? • TTL, checksum, possibly some options • If fragmentation performed, then fragmentation flag, offset,& length change. • Will datagram fragmentation change the sequence number in a TCP segment? • No. • If a piece of fragmentation is missing, what will happened at TCP layer? • Eventually, TCP will timeout or get duplicate acks. Source node will retransmit. • In its peak, spam consists of ___% of email traffic as of July 2004. Its share is ___% in July 2005. • 94.5%, 64.2%

  10. IP Quiz • What is the IP broadcast address? • 255.255.255.255 • Netid+all 1s. • What is the broadcast address of an Ethernet card? • FF-FF-FF-FF-FF-FF. • Suppose a datagram is 1000byte. The MTU is 500 byte. How many fragments do you need? • three (because of the IP header). • When was Yosemite established as a National Park? • 1890. • How many times have u been there?

  11. IP Quiz • Where have we discussed tunneling? • IPv6/v4 and mobile IP. • Name the main changes of IPv6 over v4. • Is the network prefix length included in IP header? How could a router tell? • What is ICANN? • Internet Corporation for Assigned Names and Numbers • Allocate IP address, manage DNS root servers.

  12. IP Quiz • Which routing algorithm is easier to be used by a malicious router to “crash” Internet, LS or DV? • DV. • RIP uses ___ and OSPF uses ___ (LS/DV). • DV and LS. • RIP message is carried over ___, OSPF ___, and BGP over ____. • UDP, IP, and TCP, respectively. • Suppose there are three closed doors, behind which, one has the final-exam paper, two others have the mid-term paper. Suppose you choose one (not open). Then I open one-door, which has mid-term paper. Do you want to switch your selection now? • Yes. A 2/3 probability of seeing the final exam paper now if you switch.

  13. IP • Broadcast and multicast use ____ (UDP/TCP). Why? • UDP. • What are the subnet IDs in CS? • 192.168.1.0/24 • 169.237.6.0/24 • How long is the current-known largest prime? • Over 6M digits! • A network of 200,000 computers over two years.

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