Lab 3 Week 3 Study Sheet 1

Exercise 3.2.1 Physical: The hardware such as cables, NIC card, and hub Data Link: The protocol layer that transfers data between adjacent network nodes (The switches and MAC addresses) Network: Sends the information (IP address and routers) Transport: allows communication for the application (UDP datagram) Session: manages the session between the user and the application (control and tunneling protocols)
Presentation: translates the applications encryption (SSL/TLS)
Application: this is where you see/hear the information with your own eyes/ears
Exercise 3.2.2
Application
Presentation
Session
Transport
Network
Data Link
Physical

Exercise 3.2.3 1. The data link layer checks the data-link trailer to see if the data is in error.
2. If the data is in error, it may be discarded, and the data link layer may ask for the data to be retransmitted.
3. If the data is not in error, the data link layer reads and interprets the control information in the data-link header.
4. The data link layer strips the data-link header and trailer, and then passes the remaining data up to the network layer.

Exercise 3.2.4 Because the upper layers of the OSI model are for getting the information ready to be viewed. By the time the information needs to go through the upper layers, it has already reached its destination.

Review 3.2
1) ?
2) Even though the OSI model is not directly implemented in networking, it still endures because it is basically a good “rule of thumb” and it sets a sort of idea on how things are supposed to run to keep things in standard.
3) Yes it is necessary to keep the top three layers separate because if you change one layer it minimizes the effect on the other layers also it helps your troubleshooting efforts by being able to pinpoint the suspected cause of the problem on that specific layer.

Exercise 3.3.1 The main difference between the two is that OSI has broken down the TCP/IP’s application layer to Session, Presentation, and Application. Exercise 3.3.2

Exercise 3.3.3 IP: principal communications protocol in the Internet protocol suite for relaying datagrams across network boundaries TCP: provides a communication service at an intermediate level between an application program and the Internet Protocol UDP: computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without prior communications to set up special transmission channels or data paths

Review 3.3
1) UDP would be used for the DNS), where queries must be fast and only consist of a single request followed by a single reply packet.
2) Because TCP provides communication services between the application and the IP it is very useful with HTTP because of the amount of information sent and received from a website.
Exercise 3.4.1 The MAC addresses tell you where it needs to go.
Exercise 3.4.2 Frame 1: Hexadecimal: 01:80:c2:00:00:00
Exercise 3.4.3 Internet protocol version 4

Exercise 3.4.4

Source fc:99:47:22:E3:81
Destination 01:00:5E:00:00:0A
Exercise 3.4.5 DHCPv6
Review 3.4
1) Alone, Wireshark is not a significant threat, provided that no hubs are used on a network and switches are not attacked then a user running Wireshark will only see traffic from their own host.
2) IP Address. Payload length, Next header, Hop Limit, Source, and Destination

Exercise 3.5.1
Computer name: Meat
Workgroup name: Potatoes
Review 3.5
1) The risk of enabling file sharing is that anyone on any computer connected to the work group you have created can access your files. You should only do this for computers that need to exchange files frequently and that do not have sensitive material on them.
2) The risk of enabling a shared printer is by enabling File and Printer sharing, you are enabling other computers on your network to access your shared files and folders through port 80 which, is the same port that web browsers use to connect to the internet.

Resources Used: http://freeccnastudy.blogspot.com/2012/01/encapsulation-and-de-encapsulation.html http://freeccnastudy.blogspot.com/search?q=osi+model http://www.dummies.com/how-to/content/getting-to-know-the-osi-model-for-the-ccna-exam.html http://technet.microsoft.com/en-us/library/cc786900(v=ws.10).aspx