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Prepare for your midterm exam with this comprehensive study guide covering protocols, calculations, and knowledge questions related to computer networking.
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Midterm Exam Review • Release questions via webcourse “assignment” around 10:30am, Thur. Oct. 25th, due via webcourse at 10:30am next day • Submit format: • Word file, PDF file • Scanned answer sheets • Make sure your writing is large and readable • Photos of your answer sheets if you have no scanner • Make sure it is readable • You can resubmit, so submit first version early! • From 10:30am to 1pm, you can call me for any questions related to exam problems • Office number: 407-823-5015 (HEC 243)
Question Types • Knowledge questions • True or false statement (explain why) • Protocols • Calculations
Knowledge Question Examples • Difference between TCP and UDP? • Why UDP is better than TCP in some applications? • How many layers in computer networking? • What’s usage of TTL field in DNS record? IP packet? • Why asymmetric speed in DSL and Cable Modem? • What service port used by DNS, HTTP, SMTP, SSH, POP3,etc? • Why use window in TCP packet transmission? • What service provided by DNS? • TCP or UDP used in which applications (HTTP, SMTP, DNS, VOIP, etc)?
Knowledge Question Examples • What is HTTP cookie used for? • TCP socket programming: • the basic socket APIs and their orders • (Page 13, Chapter2-part3.ppt) • TCP/UDP header fields, header size (Page 3, Chapter3-part3.ppt) • User email agent uses the same protocol for sending/receiving email? • Why email with an attachment sent out is much bigger than the attachment? • What is a torrent file? A tracker in BitTorrent? • Ethernet switch checks what layer’s header? Router?
Protocol Problem Examples • Show what sender/receiver reacts when a specific incident (bit-error, lose, timeout) happens • Use graph to show interactions for TCP’s SR or GBN • Example (P.16 in Chapter3-part2.ppt) • Show for rdt3.0 (no test on rdt1.x to rdt2.x) • Example (P. 7,8 in Chapter3-part2.ppt) • TCP syn/ack number changes in a connection • Example (P. 5, Chapter3-part3.ppt) • Draw packet transmission time-line scenario • Example (P. 14, 15, Chapter3-part3.ppt) • TCP three-way connection setup procedure • SYN, SYN/ACK, ACK and changes of seq/ack number • Example (P.25, chapter3-part3.ppt) • Connection closing (P.26, chapter3-part3.ppt)
Protocol Problem Examples • Why TCP delays its ACK “Wait up to 500ms for next segment. If no next segment, send ACK”? • DNS RR entries setup for an Email/Web server in a company (HW1, problem 4) • TCP AIMD (HW2, problem 6) • Email SMTP command and manual send spam • HTTP protocol • TCP congestion window low-pass filter (estimate RTT) • Formula in P. 7, chapter3-part3.ppt
Calculation Problem Examples • Proxy impact (access time) • HW1, problem 5 • UDP checksum calculation • HW2, problem 2 • Packet switching advantage • HW1, problem 1 • TCP window usage • HW2, problem 7
Try to go over 2 homework's problems • Try to go over my lecture notes • Covers until and including transport layer