CIS 4930 - Computer Networking Midterm Test Questions with Correct Answers Latest Update

CIS 4930 - Computer Networking Midterm Test Questions with Correct Answers Latest Update Hosts/End Systems - Answers devices connected to the internet sit on network edge Ex: Laptops, Smartphones, Tablets, TV's etc -servers (Web and e-mail) -desktop computers Communication Links - Answers connects end systems made up of different physical media: - coaxial cable - copper wire - optical fiber - radio spectrum Transmission Rate - Answers The rate at which data is transmitted (bits/second) Packets - Answers segments of messages that contain digital instructions that allow them to reassemble properly at the same time at the destination - travels through communication links and packet switches - rate = full transmission rate of link Ex: source host sending packet of L bits over a link with rate R bits/sec then time = L/R seconds Packet Switch - Answers takes a packet arriving on one of its incoming communication links and forwards that packet on one of its outgoing communication links Types: - routers - used in network core - link-layer switches - used in access networks Internet Service Provider (ISP) - Answers The way end systems access the Internet They are interconnected -Lower Tier - National and International Upper Tier -access ISP - Regional ISP - IXP - Tier ISP -peers on the same level Types: - Residential ISPs: - local cable - telephone companies - Corporate ISPs - University ISPs - ISPs that provide Wifi to public places - Cellular Data ISPs - mobile access to smartphones ISP Access Types - Answers - Residential Broadband Access: -Cable modem -DSL - High-Speed LANs: - Mobile Wireless Access Protocols - Answers defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event. Types: -TCP (Transmission Control Protocol) -IP (Internet Protocol) -HTTP (for the web) -SMTP (for e-mail) Internet Standards - Answers Developed by the Internet Engineering Task Force (IETF) The documents are called RFC (Request for comments) -Technical -Resolve network and protocol design problems Distributed Applications - Answers Applications that involve multiple end systems that exchange data with each other - Music streaming from the cloud - mapping with real-time information Client/Server - Answers A host/end system can be divided into these two parts -Client : desktop, mobile PCs -Server: powerful machines that store/distribute web pages, stream video etc. Data Centers - Answers Large numbers of network servers used for the storage, processing, management, distribution, and archiving of data, systems, Web traffic, services, and enterprise applications. Home Access Networks (DSL) - Answers DSL (Digital Subscriber Line): -residential -from telephone company -teleco is also ISP in this case -telephone line(twisted-pair copper wire) to exchange data with DSLAM(digital subscriber line access multiplexer) located in central office. -DSL modem in home takes digital data and translates to high-frequency tones for transmission. - Analog signals from houses translated back to digital format at DSLAM. Frequencies: -high-speed downstream channel 50kHz to 1MHz band -medium-speed upstream channel 4kHz to 50kHz band -ordinary two-way telephone channel 0 to 4kHz band -meant for short distances -asymmetric access: less rates than stated Home Access Networks (Cable) - Answers makes use of the cable television company's existing cable television infrastructure - fiber optics connect the cable head to neighborhood-level junctions - coaxial cable is then used to reach individual houses and apartments. - each neighborhood junction: 500-5000 houses - HFC (hybrid fiber coax) - Cable modem used via Ethernet port - CMTS turns analog to digital - Cable modems divide HFC network to upstream and downstream channels with asymmetric access. -Shared broadcast medium -slower rate if multiple users are using downstream - also high downstream rates when many users are web surfing -Downstream-from homes -Upstream-to television company Home Access Networks FTTH (fiber to the home) - Answers A service in which a residential