Homework Questions

Please answer all of these questions on your personal blog and explain. Don’t just give an answer. Homework is due Sunday night at 6 pm

IP Addresses

  1. Which of the following IP Addresses are possible? Explain (yes/no) for each answer choice.
    • 1.1.1.1.1 NO (more than 4 digits )
    • 23.23.23.23 YES (fits 4 digits)
    • 134.492.100.0 NO (492 over limit)
    • 255.256.55.255 NO (256 over limit)
    • 2.93.255.19 YES (fits all reqs - 4 digit limit and number cap)
  2. If Dian Du is at home on his home network and sends a message to every computer on the network, what is this an example of? Explain.
    • Multicast
    • Unicast
    • Broadcast THIS ONE because broadcast is all computers on a network

Models

  1. Three of the four following protocols are on the same layer. Identify which ones and what layer they are on, and why they are on each layer:
    • ASCII (see above for information):
      • Application layer (handles exchanging information for its displayed characters)
    • FTP (facilitates transfer of files over the internet)
      • Application Layer - communicates files used by applications to provide user services and exchange data
    • TLS (see HTTPS section)
      • Application Layer as its part of HTTPS along with SSL and handles application encryptoon
    • USB (permits data exchange between electronics)
      • Physical Layer transfers files through physical means
  2. Telnet is a internet protocol which allows remote access to other computers over a local network or the internet. What layer of the OSI model would this protocol be located on? What is the function of this layer?
    • Data Link layer by definition of transfering files on a local network but Application Layer in it that it connects to command lines and gives users the interface to access the network so APPLICATION LAYER

DNS

  1. Bob wants to use the domain bob.is.the.best.com. What domain should he buy from a DNS provider (assume it is available)? What would be the subdomains?
    • best.com is the domain he needs to buy
    • sub domains are the, is, and bob

HTTP and HTTPS

  1. What is a difference between HTTP and HTTPS?
    • What protocol does HTTPS use that HTTP doesn’t?
    • HTTPS is different because of the S - stands for Secure. HTTPS uses SSL/TLS protocols to encrypt the data and protect it from third parties
  2. Last trimester we sent HTTP requests for our passion projects
    • Did we use HTTP or HTTPS?
    • We used HTTP - What are the benefits and disadvantages of this?
    • More simple, faster speed. Insecure, open to malicious attack or privacy concerns

TCP and UDP

  1. Bob is setting up a video streaming service, and he needs the stream to be real time.
    • What protocol should he use, TCP or UDP? Why?
    • UDP as its super quick and doesn’t worry as much about complete perfection for every frame/data - What are some cons of this protocol? Give an example of a potential issue.
    • Little data checking = unreliable and some packets can get lost, making video quality drop
  2. TCP has error checking, which ensures that all packets arrive properly. Why is this important?
    • Gives you accuracy and reliability which is essential for tasks where small processes make big differences
      - Give an example of how TCP ensures that there are no errors.
    • mathematical verification like Checksums or sequence numbers
  3. Server A computer is communicating with Server B. They have already initiated communication and Server A is now attempting to send data to Server B.
    • How does Server B ensure that they have received any sent packets before Server A continues sending packets in TCP? In UDP?
    • Server B sends ACK packets (acknowledging that they got the packets) in TCP. UDP doesn’t do this verification in the first place, they assume some data will be lost - What is another use of this?
    • maintains control by informing the other computer of the last few bits recieved and sendinng back the ACK bit package