# Shared Flashcard Set

## Details

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

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
Definition
Term
Definition
Term
Definition
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
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
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
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
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.
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