Shared Flashcard Set

Details

CGS 4285 by Eduardo Monteiro Exam 2
CGS 4285 by Eduardo Monteiro Exam 2
105
Computer Science
Undergraduate 4
10/24/2012

Additional Computer Science Flashcards

 


 

Cards

Term

(lecture 6) IP packets are also known as ___

Definition

IP datagrams

Term

(lecture 6) Bytes in an IP packet are also known as

Definition

octets

Term

(lecture 6) IP is a layer ___ protocol

Definition

3

Term

(lecture 6) Time to Live (TTL) is?

Definition

How long before the packet is discarded

Term

(lecture 6) IP addresses are divided into what 2 parts?

Definition

Network and Host

Term

(lecture 6) IP Addresses are ___ bits

Definition

32

Term

(lecture 6) Is today's internet classful or classless?

Definition

classless

Term

(lecture 6) What are the available addresses? 131.94.0.0/16

Definition

131.94.x.x

Term

(lecture 6) what are the available addresses? 68.45.160.0/19

Definition

68.45.160-191.x

Term

(lecture 6) What are the available addresses? 199.45.64.0/18

Definition

199.45.64-127.x

Term

(lecture 6) Network: The Host portion of the network address is filled with ___

Definition

0

Term

(lecture 6) Network: The Host portion of the broadcast address is filled with ___

Definition

1

Term

(lecture 6) What are the network and broadcast addresses? 131.94.133.12/16

Definition

Network: 131.94.0.0/16 Broadcast: 131.94.255.255

Term

(lecture 6) What are the network and broadcast addresses? 68.45.167.245/19

Definition

Network: 68.45.160.0/19 Broadcast: 68.45.191.255

Term

(lecture 6) What are the network and broadcast addresses? 199.45.78.199/18

Definition

Network: 199.45.64.0/18 Broadcast: 199.45.127.255

Term

(lecture 6) How many /24 are in a /16?

Definition

2^(24-16) = 2 ^8 = 256 new subnets

Term

(lecture 6) How many /26 are in a /22?

Definition

2^(26-22) = 2^4 = 16 subnets

Term

(lecture 6) How many /28 are in /26?

Definition

2^(28-26) = 2^2 = 4 new subnets

Term

(lecture 6) What is 127.0.0.0/8?

Definition

It is a loopback network where traffic loops back to the sender

Term

(lecture 6) What is 255.255.255.255?

Definition

It is a non-directed broadcast address which will reach all hosts on the network.

Term

(lecture 7) How do you calculate how many subnets can be created by increasing the netmask.

Definition

2 ^(y-x)

Term

(lecture 7) 200.45.60.0/22 is 1 network with 2^10 hosts (1024). How do we get ? networks that can accommodate 50 hosts each?

Definition

by using a /26 subnet

Term

(lecture 7) How many /26 subnets are in a /22 network?

Definition

2^(26-22) = 2^4 = 16 subnets

Term

(lecture 9) What is ARP's job?

Definition

To take an IP address and find out which ethernet address is associated with it

Term

(lecture 9) ARP is technically which layer?

Definition

It's technically a Layer 3 protocol but only works on the network it operates on.

Term

(lecture 9) Are ARP requests routed?

Definition

No

Term

(lecture 9) ARP can be considered a glue between which Layers?

Definition

Layers 2 and 3.

Term

(lecture 9) If Station A needs to find the Ethernet address associated with station B's IP address, what steps must be done with ARP?

Definition

1. is the information in the ARP's cache? Yes: Create Ethernet frame and send it directly to B No: Go to step 2

2. Send out a broadcast ARP request asking all hosts what is the Ethernet address associated with B's IP address

3. Station B should send back an ARP reply to A with its Ethernet address

4. Station A puts B's information in the ARP cache

Term

(lecture 8) When a router receives a packet, it follows what steps?

Definition

1. Is it one of my addresses? Yes: Process the packet No: Go to step 2

2. Is it on a network that I'm connected to? Yes: send the packet through the interface connected to that network No: go to step 3

3. Is it on a route in the Routing Table? Yes: send it to the next hop No: send it to the default route

Term

(lecture 8) What is a Next Hop?

Definition

Next Hop is the address to a device that can get the data packet closer to its destination address.

Term

(lecture 8) When the destination address does not match any entries in the routing table, where do we send it?

Definition

The default route

Term

(lecture 8) What does every Routing Table need to operate on the internet?

Definition

A default route

Term

(lecture 10) IP packets can be as large as ___ bytes.

Definition

65535

Term

(lecture 10) What is IP Fragmentation?

Definition

Divide the IP packet into smaller pieces that will fit within the MTU of the Layer 2 frame being used

Term

(lecture 10) When the total length is greater than the MTU of the underlying Layer 2 network, what is needed?

Definition

IP Fragmentation

Term

(lecture 10) What are the two flags of IP Fragmentation?

Definition

DF - Don't Fragment

MF - More Fragments

Term

(lecture 10) To find out the actual Fragment offset multiply this field by ___ to get the number of bytes.

Definition

8

Term

(lecture 10) To know the value of the Fragment Offset field, divide by ___ if you have the offset in bytes.

Definition

8

Term

(lecture 10) How do you determine how many fragments are needed?

Definition

Divide the (IP Packet Length – IP Header Size) by (MTU - IP Header size) and round up. (MTU – IP Header size) must be a multiple of 8. In other words, the size of the data fragment is bounded by 8 bytes

Term

(lecture 10)
IP packet Length = 4096
MTU = 1500
IP Header Length = IHL field value x 4 = 5x4 = 20.
How many fragments are needed?

Definition

(4096 – 20) / (1500 – 20) = 4076 / 1480 = 2.75 = 3 fragments

Term

(lecture 10) In IP Fragementation, initial data will be split into chunks of ____ bytes or less to fit within the MTU limits.

Definition

1480

Term

(lecture 10) In IP Fragmentation, if any fragment is lost, what happens?

Definition

The reassembly will timeout and the entire packet will be dropped. All fragments will have to be sent again.

Term

(lecture 10) Is IP Fragmentation TCP?

Definition

No, TCP is Layer 4.

Term

(lecture 10) IP fragmentation happens when the IP packet is ___ than the MTU of the Layer 2 below

Definition

larger

Term

(lecture 10) In IP Fragmentation, an IP packet is divided into smaller fragments, on a ___ byte boundary

Definition

8

Term

(lecture 10) In IP Fragmentation, the receiver will start a ___ upon receiving a fragment.

Definition

Timer. If the timer expires and fragments have not arrived, it will drop the entire packet.

Term

(lecture 10) MF bit and Fragment Offset (FO) field If MF = 1 and FO = 0

Definition

First Fragment

Term

(lecture 10) MF bit and Fragment Offset (FO) field If MF = 1 and FO != 0

Definition

MIddle Fragment

Term

(lecture 10) MF bit and Fragment Offset (FO) field If MF = 0 and FO != 0

Definition

Last Fragment

Term

(lecture 10) MF bit and Fragment Offset (FO) field If MF = 0 and FO = 0

Definition

Not a fragment. Just a regular Packet.

Term

(lecture 10) ICMP stands for?

Definition

Internet control Message Protocol

Term

(lecture 10) ICMP is a Layer ___ protocol used to signal information about Layer ___ events.

Definition

4, 3

Term

(lecture 10) ICMP is called an ___ signaling protocol

Definition

in-band

Term

(lecture 10) What is ICMP useful for?

Definition

diagnostics about hosts and networks and routers.

Term

(lecture 10) What is ICMP Type 3?

Definition

Destination unreachable message

Term

(lecture 10) What is ICMP Type 5?

Definition

Redirect

Term

(lecture 10) What is ICMP Type 8?

Definition

Echo Request (ping)

Term

(lecture 10) What is ICMP Type 0?

Definition

Echo Reply (ping response)

Term

(lecture 10) What is ICMP Type 11?

Definition

TTL Exceeded

Term

(lecture 10) Traceroute program actually ___ the ICMP protocol to gather information about routes.

Definition

exploits

Term

(lecture 10) How does Traceroute work?

Definition

Initially sends packets with TTL=1. When first hop sees a packet, it decrements TTL and sends back a TTL exceeded message. Traceroute writes down the information about this first hop and sends more packets, now with TTL=2. The first hop decrements the TTL=1. Second hop sends back TTL exceeded message. Traceroutes repeats this process, increasing the TTL and sending packets until the destination is reached

Term

(lecture 11) How many available ports are there?

Definition

65535

Term

(lecture 11) Which ports are reserved by the system and used for well known applications and protocols.

Definition

1-1023

Term

(lecture 11) ports 1024-65535 are called ___ ports.

Definition

ephemeral

Term

(lecture 11) UDP stands for?

Definition

User Datagram Protocol

Term

(lecture 11) Multiplexing is provided by ___

Definition

UDP

Term

(lecture 11) Does UDP guarantee delivery?

Definition

No

Term

(lecture 11) For VOIP, streaming audio, or video it is best to use ___

Definition

UDP

Term

(lecture 11) TCP stands for?

Definition

Transmission Control Protocol

Term

(lecture 11) in TCP, ACK stands for?

Definition

Acknowledgement

Term

(lecture 11) In TCP, a 3 way ___ establishes a connection and negotiates parameters

Definition

handshake

Term

(lecture 11) IN TCP, active participant sends a ___ message to the passive participant

Definition

SYN

Term

(lecture 11) In TCP, passive participant sends a ___ message to the active participant

Definition

SYN/ACK

Term

(lecture 11) In TCP, during a 3 way handshake, devices negotiate a ___

Definition

receive window

Term

(lecture 11) In TCP, a ___ is the maximum amount of data a device is willing to receive before having to send back an ACK message

Definition

window

Term

(lecture 11) During a 3 way handshake, ___ ensures effective use of bandwidth so that ACKs are not needed for every segment

Definition

A window

Term

(lecture 11) In TCP, what happens when data arrives out of order.

Definition

TCP will put it back together in order

Term

(lecture 11) What are the 5 things that identify a connection or "Flow"

Definition

1. Protocol
2. Source Address
3. Source Port
4. Remote Address
5. Remote Port

Term

(lecture 11) What is TCP Flow?

Definition

When a single network connection can be multiplexed into many flows that carry data separately to each application

Term

(lecture 11) When servers listen, it's also known as?

Definition

Passive connection

Term

(lecture 11) When clients connect, it's also know as?

Definition

Active connection

Term

(lecture 12) DHCP stands for?

Definition

Dynamic Host Configuration Protocol

Term

(lecture 12) DHCP hands out information such as?

Definition

1. IP Address
2. Netmask
3. Gateway
4. Host name
5. Lease Time
6. DNS servers

Term

(lecture 12) Does DHCP work with UDP or TCP

Definition

UDP

Term

(lecture 12) With the DHCP Discover Mesage (Client > Server) what is the SrcAddr and DstAddr?

Definition

SrcAddr: 0.0.0.0 DstAddr: 255.255.255.255

Term

(lecture 12) How does the client maintain leased IP?

Definition

At 1/2 the lease time, client will make another request to the DHCP server

Term

(lecture 12) What are the 3 private IP addresses?

Definition

10.0.0.0/8
172.16.0.0/12
192.168.0.0/16

Term

(lecture 12) Can Private IP addresses be routed on the internet?

Definition

No

Term

(lecture 13) What does DNS stand for?

Definition

Domain Name System

Term

(lecture 13) What does DNS do?

Definition

In order to make it easier to find hosts on a network, a system was developed to associate a name to an IP address.

Term

(lecture 13) In DNS, the first "." is the?

Definition

Root Zone

Term

(lecture 13) In DNS, edu would be?

Definition

A top level domain server delegate to second level domain server

Term

(lecture 13) In DNS, fiu would be?

Definition

Second level domain that may have a sub zone.

Term

(lecture 13) In DNS, www would be?

Definition

The machine name

Term

(lecture 13) DNS servers can be what 3 types?

Definition

Authoritative, Resolver, and Caching

Term

(lecture 13) In a DNS record type: A means?

Definition

Address

Term

(lecture 13) In a DNS record type: MX means?

Definition

Mail exchanger

Term

(lecture 13) In a DNS record type: CNAME means?

Definition
Canonical name(alias
Term

(lecture 13) In a DNS record type: NS means?

Definition

Name server

Term

(lecture 13) In a DNS record type: SOA means?

Definition

Start of Authroity

Term

(lecture 13) In a DNS record type: PTR means?

Definition

Pointer (Reverse DNS - finding the name when you have the number)

Term

(lecture 13) In DNS, what would happen if you were looking for www.cis.fiu.edu?

Definition

1. A Host crafts a DNS UDP packet asking for the A record of ww.cis.fiu.edu and sends it to port 53 of the configured DNS resolver.
2. Resolver sends NS query for the “edu.” top level domain to one of the Root Servers.
3. Root server replies with list of name servers for the edu. Zone.
4. Resolver sends another NS query to one of the servers in the reply of 3, now asking for fiu.edu.
5. It gets another list of servers. It then sends another NS query for cis.fiu.edu. To one of the servers in this list.
6. Resolver gets a list of name servers for cis.fiu.edu.
7. Resolver sends an A record query for www.cis.fiu.edu to one of the servers in 6.
8. Resolver receives an IP address as a response.
9. Resolver forwards the above response to the host that was asking for it in step 1.

Term

(lecture 7) In a IP Packet, IHL stands for?

Definition

IP Header Length - Length of the IP header as a multiple of 4 bytes. If value is 5, then IP Header is 20bytes long.

Term

(lecture 7) In a IP Packet, TOS stands for?

Definition

Type of Service - Usually 0. High throughput, high reliability, low cost

Term

(lecture 7) In a IP Packet, TTL stands for?

Definition

Time to live - How long before this packet is discarded.

Supporting users have an ad free experience!