Exam Two Flashcards
While IP addresses are tied to specific networks, Ethernet addresses are not.
think of a good reason why they are not?
Ethernet addresses are used on the same network. (why is this?)
Mac addresses are used for internal communication inside the computers
verify
What are ICMP Messages for? What do they do? Name some.
They are protocols that allows for error messages to be sent like ping or echo nad arp
ICMP messages Internet Control Message protocol
-Hello packet
-Message expired
H3b.8 Describe what ARP does (why it is necessary) and how it works.
Arp is a way for a router to find out what MAC Address is of each computer so that it can send the information to the proper place.
NEED TO UNDERSTAND THIS FOR THE TEST
WHAT ARP DOES
Data link layer doesn’t know anything about IP address so we need to convert the ip address to the mac address so we can send the message to a specific mac.
HOW ARP WORKS
Broadcasts to all computers in the room with a MAC destination Address of all FFFFFFF. Asks: “who has this IP address” and then the other computer replies
H3b.9 Describe what DHCP does (why it is necessary) and how it works.
Client sends out a DHCP discover packet that asks: “Who here is a DHCP Server
DHCP is a protocol that allows servers to assign IP addresses to computers within a network. They also have a refresh time that allows more computers onto the internet. For example USU’s is set to lease the IP address for 10min before a computer has to ask for another IP address
How many DHCP servers should be in one broadcast domain? Why?
You shouldn’t have more then one or you could have duplicate address handed out which will cause errors
True / False If your computer obtains an IP address dynamically thru DHCP, that IP address will always change.
False, it depends what the DHCP server’s settings are on leasing IP’s
If the Transport layer (and its primary addressing system) didn’t exist, what would we lose the ability to do?
We would be unable to make the transition between hardware and software
—(Answer)We would not be able to have multiple applications running on the same IP address.
H4.2 What advantages does TCP offer over UDP? Name a service that would work better over TCP.
TCP is like Certified mail you get a verification that your packet arrived
Email is better over TCP
What advantages does UDP offer over TCP? Name a service that would work better over UDP.
UDP is a send and forget protocol.
Live streaming is better over UDP
4 (2 points) Is DHCP a UDP packet? Why?
DHCP does use UDP.
The server doesn’t want to have to retrieve verification from everybody that accepts their IP Address. The DHCP server wants to be able to send out IP addresses and forget about it.
You have port scanned an IP address and know what ports the server is listening to Using the following results, what services might be running on that machine?
(know for test) What if we were limited to just one door as a client ---- you couldn’t download more then one file at a time. Know door 80 web server know door 25 is email based communication. Secure web https 443 Ip address: port is called a socket 129.123.20.12:21 LISTENING File Transfer Protocol (FTP) 129.123.20.12:42 LISTENING Host Name Server Protocol[29] 129.123.20.12:25 LISTENING Simple Mail Transfer Protocol (SMTP) 129.123.20.12:4990 LISTENING Apple IPlay uses ports 4990-4999
What is the Addressing Schema and Protocols of Physical Layer
Addressing schema= Not applicable
Protocols= Amplitude modulation, Frequency Modulation
What is the Addressing Schema and Protocols of Application Layer
Address Schema=DNS
Protocols=HTTP, SMTP, FTP
What is the Addressing Schema and Protocols of Data Link Layer
Address Schema=MAC
Protocols=Ethernet
What is the Addressing Schema and Protocols of Transport Layer
Address Schema=Ports
Protocols=TCP, UDP
