Exams

Midterm Exam

The class has chosen to write the midterm exam.

Each student is required to submit four unique, suitable exam questions.  They should be “thinking” questions that are not too long for an exam.  One can be homework (state which one that is).  One should be easy, two of medium difficulty, and one difficult.  Submit questions and answers.

Questions should be submitted to exam@csci6433.org.

The questions need to be unique.  If a question is submitted that has already been approved, the submitter will be told and given a chance to resubmit.

All questions are to be submitted and approved by October 18, to provide time to study before the midterm.

Although the answers will not be posted, you are encouraged to study together in any way you wish, including posting and assembling a list of questions and answers.

TopicQuestion
ARPARP is often cited as a security weakness. Explain why.
ARPExplain the main difference between ARP and RARP.
ARPCan ARP be used on a network that does not provide broadcast? Why or why not?
ARPNot using checksums can be dangerous. Explain how a single corrupted ARP packet broadcast by machine P can make it impossible to reach another machine, Q.
ARPARP spoofing attack is a security issue in switching network environment, can you find a method to mitigate this?
BGPSuppose BGP router A sends a BGP path vector to BGP peer router B. BGP peer B is connected to BGP peer C. Must B advertise that path to C?
DHCPYou want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this and is that done?
EthernetHow does what an Ethernet switch does differ from what an Ethernet hub does?
EthernetWhat is the difference in terms of network traffic between two Ethernet segments connected by a bridge and two segments connected by an adaptive bridge? Why?
Ethernet Is it necessary to use an IP checksum when sending packets over an Ethernet? Why or Why not?
EthernetIf a switch receives a frame and the source MAC address is not in the MAC address table but the destination address is, what will the switch do with the frame?
EthernetUsing network hubs may put your online credentials at risk of getting stolen, do you know why? Can you explain?
GeneralWhat are checksum field used for?
GeneralCould we use a single checksum for complete IP message without using UDP checksum?
GeneralWhat is the Good Citizen Principle?
GeneralFrom the standpoint of protocol design, what is the most critical resource on the Internet?
GeneralSuppose each person on the planet had a smart phone, laptop computer, and ten other devices that each had an IPv6 address. What percentage of the IPv6 address space would be required?
GeneralWhat are four general principles of designing Internet Protocols? Briefly explain each.
GeneralWhich is better for data networks: circuit switching or packet switching? Why?

GeneralWhy is it that voice and video traffic is often sent over TCP rather than UDP in today’s Internet?
GeneralWhich layers in the Internet protocol stack does a host process? Which layers does a router process?
GeneralWhat is the difference between direct and indirect delivery?
GeneralLayered protocols hide all underlying details from applications. Could application software be optimized if an application knew about the underlying networks being used?
GeneralWhich is better, UDP or TCP? Why?
GeneralWhat is one advantage and one disadvantage of layered network protocol?
GeneralInternet protocols sometimes violate the layering principle. Why? Give two examples.
GeneralWhy is the Internet so successful? Give two reasons.
GeneralWhich condition is better, LAN MTU higher than WAN MTU, or WAN MTU higher than LAN MTU? Why?
GeneralIf you had network adapters with changeable MAC addresses, and you set the MAC address to be the same as the IP address for each adapter, would the Internet still work? What would change?
ICMPHow does traceroute use ICMP message (suppose traceroute is implemented by ICMP)? How many messages involve in this process totally (without considering duplicated sent messages)?
ICMPHow does ping use ICMP messages, and which ones does it use?
ICMPHow will you ping the loopback address of your local host with IPv4 and IPv6?
ICMPCan an IP datagram carrying an ICMP message, if it causes an error, cause another IP datagram to be sent with an ICMP message about the first ICMP message? Why?
ICMPWho sends ICMP messages and what is the destination?
IPHow does the IP addressing scheme differ from the U.S. telephone numbering scheme?

IPWhat are the advantages of doing reassembly of fragments at the ultimate destination, rather than after the datagram traverses a single network?
IPEach IP address has a subnet mask that can help determine which subnet is it in. We can do and operation (&) on each IP address with its subnet mask, and if the result is the same, then we know that this two IP address is in the same subnet.
IPWhat is the role of IP in the TCP/IP protocol suite?
IPHow many IP address can one host have?
IPWhy should datagrams be fragmented?
IPHow can a host find the MAC address of another computer on the same network?
IPHow many computers can be setup with the network address 192.168.1.0/24 network.
IPSuppose the internet design was changed to allow routers along a path to reassemble datagrams. How would the change affect security?
IPYou want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this and is that done?
IPFragmentation and reassembly are different for IPv4 and IPv6. Which is better? Why?
IPHow is the TTL field used to prevent indefinite looping of IP datagrams?
IPv6What are some of the modifications of IPv6, from the IPv4, that allow a router to process a packet quicker?
IPv6Explain three important reasons for the new approach to fragmentation taken by IPv6.
MPLSWhat is the significance of MPLS?
MPLSHow do LSRs change MPLS headers?
MPLSIn what ways does CISCO's Multi- Layer switching, MLS differ from MPLS?
MulticastWhat happens when I ping a multicast address? Why?
MulticastWhat are three applications that can benefit from IP multicast.
NATWhat kinds of applications cannot run through a NAT box?
NATCan a local address in a network behind a NAT box be the same as a globally unique address? Explain.
NATNAT is a very important feature of IPv4. Does IPv6 need NAT?
Why or why not?
NATGive two important advantages of NAT and two important disadvantages of NAT
RoutingShould the routing table contain IP address or MAC address of next machine? Why?
RoutingRouters send HELLO datagram->Building neighbor relation->Generating link state->Getting the best path by SPF algorithm->Getting a routing table
RoutingWhy do link state protocols have better convergence rate than distance vector protocols?
RoutingWhen does a router modify the hop limit (or time-to-live) field in a datagram header?
RoutingHow does a router know whether an incoming datagram carries a routing update message?
TCPA single lost TCP acknowledgement does not necessarily force a retransmission. Explain why.
TCP What is the minimum value for the timeout of a reliable transmission protocol? Why is there a minimum value?


TCP Can two programs both use the same TCP port on the same machine at once?
UDPWhy is UDP checksum separate from IP checksum?
UDPSuppose that I have decided to use UDP to transfer data to my application. My application needs to receive the data in the order it was transmitted. Will this be a problem with UDP? If it is, how can I solve the problem?
UDPUDP is unreliable and connectionless protocol. Why do we use it?

Final Exam

The class has chosen to write the final exam.

Each student is required to submit four unique, suitable exam questions.  They should be “thinking” questions that are not too long for an exam.  One can be homework (state which one that is).  One should be easy, two of medium difficulty, and one difficult.  Two are to be from period before the midterm, two after the midterm.  Submit questions and answers.

Questions should be emailed to exam@csci6433.org.

The questions need to be unique.  If a question is submitted that has already been approved, the submitter will be told and given a chance to resubmit.

All questions are to be submitted and approved by November 29, to provide time to study before the midterm.

Although the answers will not be posted, you are encouraged to study together in any way you wish, including posting and assembling a list of questions and answers.

TopicQuestion
HTTPWhat is the difference between PUT and POST?
HTTPWhat are the differences between PUT and POST in HTTP?
IPWhy is the UDP checksum different from the IP checksum?
IPHow is TTL used to prevent router loops?
SNMPIs the command from the SNMP control center to restart the same for a UNIX machine and for a Windows machine?
PINGWhat does a successful response from PING tell you about the machine that sent the response?
EthernetIs the Good Citizen Principle used by ethernet? Explain.
SecurityWhat is a firewall? Explain.
UDPWithout changing UDP, how could an application use UDP to obtain reliable communications?
UDPHow does UDP handle an undeliverable IP datagram? Is this different from other protocols? Explain
UDPHow would you change UDP so that it could provide reliable communication?
ICMPWhat happens if an ICMP message is undeliverable?
AddressingHow is a MAC address different from an IP address?
SMTPWhat are the key steps for SMTP to transmit a message?
SMTPDoes SMTP provide assured dellivery of messages to users?
DNSGive 3 important advantages and 3 important disadvantages of DNS caching.
DNSDescribe the step-by-step process of DNS resolution when a user enters a domain name into a web browser.
DNSWould you recommend changing DHCP to deliver the URL instead of the IP address of the DNS server?
RoutingWhen will the split horizon technique prevent slow convergence?
IoTHow can IoT devices use SMTP? Explain.
SNMPWhat is the role of the MIB in SNMP and how does it contribute to machine independence?
NAT Compare how NAT works for outbound and inbound communication.
GeneralWhy can packets arrive out of order?
GeneralWhat's the difference between the roles of a router and switch in a local network?
GeneralSuppose you have to send an email to your aunt in ASIA from the us. Draw a diagram to show how the packets will reach its destination if NAT is involved on both ends. Show all addresses within the data that is transferred.
GeneralWhy is the Good Citizen Principle important?
GeneralExplain the soft state principle
GeneralFrom the standpoint of protocol design, what is the scarcest resource on the Internet?
GeneralWhy use port numbers when we could identify processes by the process ID on each machine?
SMTPWhat is the role of the MX record in email transmission?
IPHow does IP forwarding alter the original datagram?
EthernetHow does a switch reduce broadcast traffic and ARP traffic?
DNSExplain how a DNS poisoning attack works and outline measures that can be taken to prevent it.
VPNWhat are the comparative advantages and disadvantages of split tunneling and full tunneling VPN implementations?
FTPWhat protocols does FTP use?
FTPWhy does FTP use two TCP connections for a transfer?
FTPHow many connections does FTP use? Why?
FTPCompare active and passive FTP with regard to security and data transfer and NAT.
TelnetCompare Telnet and SSH for remote terminal access.
SMTPWhat protocol does SMTP use to transmit messages? Explain.
IMAPWhat's the difference in server resource utilization between IMAP and POP?
DHCPList four items of information that a host needs upon connection to the internet.
AddressingWhat is the primary purpose of using subnetting in IP addressing?
TCPIn what scenario would UDP be preferred over TCP? Give a specific example.
VPNHow does a VPN contribute to secure mobile communications?
SocketsHow does a program specify a process to connect to?
HTTPWhy was HTTP designed as a stateless protocol?
ICMPHow does ICMP violate the layering principle?