Routing

1. Who routes packets?
1. The sender
2. The receiver
3. Routers on the way
4. None of these
2. Suppose I send two packets from the same source to the destination.  Will both packets take the same route?
1. Yes
2. No
3. Maybe
3. (Two points) Consider the network described below.  What does is the routing table for computer Able after two information changed using the Ford algorithm?
   Able connects to Baker with cost 3 ms
   Able connects to Delta with cost 5 ms
   Delta connects to Echo with cost 19 ms
   Backer connects to Echo with cost 11ms
   Frank connects to Gram with cost 3ms
   Echo connects to Henry with cost 9ms
   Able connects to Echo with cost 100ms
   
   
   
4. Using the network above, what is the route with the lowest number of hops between Able and Echo?
   
   
   
5. Does NMU use the Ford algorithm to route stuff inside NMU?
1. Yes
2. No

1. Suppose my ethernet card is broken, and keeps transmitting without stopping.  What do I notice about the network performance?
   
   
   
2. Suppose that my ethernet card is working fine.  However, some fool is playing with the ethernet wire, adding and subtracting voltages in a random way every once in a while.  Will my ethernet card ever accept corrupted data?
1. Yep, that will likely happen if you wait for a while
2. Nope, that will literally never happen
3. Actually, it's unlikely to happen, but it might
3. How are ethernets wired (I mean normal modern ethernets, like NMU has)
1. In a line or bus all strung togther
2. In a loop or ring or circle
3. In a tree
4. None of the above
4. I have an ethernet card on a 100megbit ethernet.  I want to send a 1Kbyte message.  The latency is 3ms.  The number of hops is 1.  The CPU is an Intel 786.  There was a collision in the last minute, but when I send there will be no collision.  How long will it take for the receiver to get the message?
   
   
   
   
5. Suppose the ethernet card sends, and there is no collision, but the receiver doesn't get the message because the receiver is powered down.  How many times will the ethernet retansmit before it gives up?

1. (Yes/No) Suppose that you call read, and the first argument is a twelve.  Will you ever receive more than 12 bytes from that read?
2. Suppose that you go to write data down a socket, but you have yet to call accept to connect.  What will write return?
3. You are a client.  You did connect to the server succesfully, but now the server is dead.  Which system call will give you an error?  Choose all the apply.
1. gethostbyname
2. socket
3. read
4. write
5. none of the above
   
   
   
4. You are a server.  How can you tell if someone has connected to you?
   
   
   
   
5. Below is some code.  Fill in the blank to send the string, without sending a null byte at the end.
   char message[10000];
   strcpy(message, "Hi there mom I really .... .... ...");  // goes on for a long time
   len = write(fd, message, __________________________________________________);
6. (Eight points) Is there a server running on googee at port 6000?  Show me the code to decide this.
   
   

1. Suppose I want to translate www.fighterjet.org into an IP number.  How long will this likely take?
1. 1 second
2. 50 milliseconds
3. one thousandth of a second
4. a few minutes
2. Which are true (circle all that are true)
1. Any domain name can have more than one IP number associated with it
2. Any IP number can have more than one domain name associated with it
3. Every IP number has exactly one name
3. (Yes/No) I'm on a JetBomberNet, which has a maximum packet size of 972 bytes.  I want to send a 3000 byte email.  I'm using SMTP and normal email software.  Can it be done?
4. On the internet, whats the most hops two computers can be away from each other and still talk?
   
   

1. I know the MAC address for www.airplanes.com is 01:02:03:04:05:06:07:08.  How can I find out the IP number?
   
   
   
2. Every time I want to translate an IP number to a MAC address, I must transmit an ARP request, and receive an ARP reply.  What MAC address do I transmit the ARP request to?
   
   
   
3. (true/false) Every time I want to transmit an IP packet, and I must send an ARP request first.
4. Suppose you use DHCP to get an IP number.  You have a lease for five minutes.  What happens after 1 minute?
1. Nothing
2. Ask to renew
3. Lose IP number
4. CPU is ejected
5. Suppose you use DHCP to get an IP number.  You have a lease for five minutes.  What happens after 2.5 minutes?
1. Nothing
2. Ask to renew
3. Lose IP number
4. CPU is ejected
6. Suppose you use DHCP to get an IP number.  You have a lease for five minutes.  What happens after 5 minutes?
1. Nothing
2. Ask to renew
3. Lose IP number
4. CPU is ejected

1. I have a CD-ROM with holds 660 megabytes.   How long will take me to send that via a 100 megabit/second ethernet?
   
   
   
   
   
   
   
2. How does an email server verify the username of the sender of email?