7.1. Which of the following mechanisms are correct for IP (Internet Protocol) service model ?
(a) IP is connectionless service model
(b) IP is connection-oriented service model
(c) IP provides best-effort (unreliable) service
(d) IP provides reliable service
(e) IP provides global addressing scheme to identify all hosts in the Internet
7.2. Which of the following events may happen when datagrams (packets) are delivered by the IP service in the Internet ?
(a) Packets may be dropped by routers
(b) Packets may be delivered out of order
(c) Routers will retransmit packets if they are dropped by routers
(d) No duplicate copies of a packet may be delivered simultaneously in the Internet
(e) Packets can be delayed for a long time
Internetworking2 https://www.youtube.com/watch?v=eEkbkwnqPqU
7.3. Which of the following statements are correct for Routers ?
(a) A router will pass all frames received from its ports to IP layer .
(b) A router only passes frames destinated to the router to IP layer.
(c) Router uses store and forward scheme to forward incoming IP packets
(d) The Forwarding table for IP address lookup is constructed by the routing protocols, such as RIP.
(e) The IP/MAC table is constructed by the routing protocols, such as OSPF.
7.4. Which of the following are “routing protocols” ?
(a) Address Resolution Protocol (ARP)
(b) Internet Control Message Protocol (ICMP)
(c) Routing Information Protocol (RIP)
(d) Open Shortest Path First Protocol (OSPF)
(e) Border Gateway Protocol (BGP)
Internetworking3 https://www.youtube.com/watch?v=tNMDuMezkKw
Internetworking4 https://www.youtube.com/watch?v=k2WRQ-0a2Ys
7.5. Assume LAN1 and LAN2 are connected by a router R, stations A,B are connected to LAN1, and stations C, D are connected to LAN2.
Which of the following statements are correct ?
(a) When station A wants to send a packet to station B, it can send the packet to station B directly by putting the MAC address of station B into the frame.
(b) When station A wants to send a packet to station C, it can send the packet to station C directly by putting the MAC address of station C into the frame.
(c) Station A needs to know the MAC addresses of stations B,C,D in order to send frames to them directly.
(d) When station A wants to send a packet to station B, it needs to send the packet to Router R first by putting the MAC address of Router R into the frame.
(e) When station A wants to send a packet to station D, it needs to send the packet to Router R first by putting the MAC address of Router R into the frame.
Internetworking5 https://www.youtube.com/watch?v=Q9nQKJ71Nko
7.6. Which of the following “routing strategies” are correct for IP packets forwarding ?
(a) When a router receives an IP packet, it forwards the packet to the destination host if the destination network of the packet is NOT directly connected with the router.
(b) When a router receives an IP packet, it forwards the packet to some router if the destination network of the packet is directly connected with the router.
(c) Each host has a default router
(d) Hosts don’t need to know which routers are connected directly.
(e) A host will always send its packets to destination host via its default router.
a = 6
b = 5
c = 3
d = 3
e = 3
f = 3
g = 1
h = 2
Internetworking6 https://www.youtube.com/watch?v=Fld6jA_tU48
7.8. Which of the following “IP fragmentation and reassembly strategies” are correct ?
(a)Fragmentation occurs in a router when it receives a datagram that it wants to forward over a network which has MTU < datagram.
(b) Reassembly is done at the next hop router
(c) The fragments from the same datagram may carry different identifiers
(d) Fragments are self-contained datagrams
(e) IP will try to recover from missing fragments
7.9. Consider the following datagram of 1500 bytes are fragmented into three fragments. Assume the top one is the first fragment and the bottom one is the last fragment. What is the offset value for each of the three fragments ? Thus,
a 0
b 70
c 140
Internetworking7 https://www.youtube.com/watch?v=nQOWxB3wtPs
7.10. Which of the following statements are correct for “Router Characteristics” ?
(a) Router is network layer protocol independent
(b) Router will filter broadcast and multicast MAC frames
(c) Router is easy to support mixed media
(d) All packet fragmentation and reassembly will only be done by routers.
(e) Router forwards packets based on network (IP) addresses and information
Internetworking8 https://www.youtube.com/watch?v=pXDDLyYUCwo
7.11. Consider the following internetwork configuration with subnet setting. Assume that
“1” represents the interface of router R1 to network 1,
“2” represents the interface of router R1 to network 2,
“3” represents router R2,
“4” represents router R1,
“5” represents the interface of router R2 to network 2, and
“6” represents the interface of R2 to network 3.
Then for router R1, what is the “next hop” for the following received packets ?
(a) Destination IP = 128.96.34.15, Nexthop = 1
(b) Destination IP = 128.96.33.128, Nexthop = 3
(c) Destination IP = 128.96.33.2, Nexthop = 3
(d) Destination IP = 128.96.34.135, Nexthop = 2
(e) Destination IP = 128.96.34.127, Nexthop = 1
(f) Destination IP = 128.96.34.250, Nexthop = 2
Internetworking9 https://www.youtube.com/watch?v=P77gaouo3to
Internetworking10 https://www.youtube.com/watch?v=ZnTA4naO4-g
7.12 Which of the following statements are correct for “Classless Inter-Domain Routing (CIDR)” ?
(a) A technique that deal with the size problem of backbone routing table.
(b) It uses aggregate routes. Thus, uses a single entry in the forwarding table to tell the router how to reach a lot of different networks.
(c) The convention is to place a “/X” after the prefix where X is the prefix length in bits
(d) The “prefix” for all the networks 192.4.16 through 192.4.31 is represented as 192.4.16/20
(e) A single class C network number 192.4.16 is represented as 192.4.16/24
Internetworking11 https://www.youtube.com/watch?v=WjLd0Rj_Snk
7.13 With the CIDR, what is the “prefix” for all the networks 192.4.16 through 192.4.31 ? Assume the prefix is represented as 192.4.a/b, and therefore
a = 16
b = 20
7.14 With the CIDR, what is the “prefix” for all the networks 192.4.0 through 192.4.15 ? Assume the prefix is represented as 192.4.a/b, and therefore
a = 0
b = 20
7.15 With the CIDR, what is the “prefix” for all the networks 192.4.0 through 192.4.31 ? Assume the prefix is represented as 192.4.a/b, and therefore
a = 0
b = 19
7.16 With the CIDR, what is the “prefix” for all the networks 192.4.0 through 192.4.255 ? Assume the prefix is represented as 192.4.a/b, and therefore
a = 0
b = 16
7.17 Consider the following network configuration and CIDR addressing. Assume the prefix advised by the ISP is represented as 192.4.a/b. Then,
a = 0
b = 21
Internetworking12, 13, 14 https://www.youtube.com/watch?v=HjduYnh1X4E
7.18 Which of the following statements are correct for "Address Resolution Protocol (ARP)" ?
(a) It is used to map IP addresses into physical (MAC) addresses
(b) Each host has an IP/MAC mapping table to binding the IP address to physical (MAC) address
(c) For a host, if an IP address is not in its IP/MAC table, it sends an ARP request to the IP address directly by using unicast packet.
(d) When the targeted host receives an ARP request, it will respond with its physical address.
(e) Every host receives an ARP request will respond with its physical address.
7.19 Which of the following statements are correct for "Dynamic Host Configuration Protocol (DHCP)" ?
(a) For an administrative domain, there is at least one DHCP server
(b) The DHCP server is responsible for providing configuration information to hosts
(c) The DHCP server maintains a pool of available addresses
(d) Newly booted host sends DHCP DISCOVER message to an IP address = 255.255.255.254
(e) Newly booted host sends DHCP DISCOVER message to an IP address = 255.255.255.255
7.20 The Internet Message Control Protocol (ICMP) defines a collection of error messages that are sent back to the source host whenever a router or host is unable to process an IP datagram successfully. Which of the following errors will be reported by the ICMP protocol ?
(a) Destination host unreachable
(b) Reassembly process failed
(c) TTL had reached 0
(d) IP header checksum failed
(e) Dropped by router due to network congestion
Internetworking15, 16 https://www.youtube.com/watch?v=-JkAAvlIzBc
Internetworking17 https://www.youtube.com/watch?v=FQ9jdb83zwk
Internetworking18 https://www.youtube.com/watch?v=ppZA_m0iDSs
7.21 Which of the following statements are correct for “Distance Vector” routing protocol ? Assume that each node knows the cost of the link to each of its directly connected neighbors.
(a) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to all other nodes and distributes that vector to its immediate neighbors.
(b) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to all other nodes and distributes that vector to all other nodes.
(c) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to its immediate neighbors and distributes that vector to all other nodes.
(d) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to its immediate neighbors and distributes that vector to its immediate neighbors.
(e) fast response to “good news” and slow response to “bad news”
7.22 One technique to improve the time to stabilize routing is called “split horizon”. Which of the following statements are correct for “split horizon” ?
(a) When a node sends a routing update to its neighbors, it only sends those routes it learned from each neighbor back to that neighbor.
(b) When a node sends a routing update to its neighbors, it does not send those routes it learned from each neighbor back to that neighbor
(c) When a node sends a routing update to its neighbors, it sends all routes it learned to those neighbors.
(d) When a node sends a routing update to its neighbors, it sends those routes it learned from each neighbor back to that neighbor with negative information (such as ∞).
(e) When a node sends a routing update to its neighbors, it sends all routes it learned to those neighbors with negative information (such as ∞)..
7.23 Which of the following statements are correct for “split horizon with poison reverse” scheme ?
(a) When a node sends a routing update to its neighbors, it only sends those routes it learned from each neighbor back to that neighbor.
(b) When a node sends a routing update to its neighbors, it does not send those routes it learned from each neighbor back to that neighbor
(c) When a node sends a routing update to its neighbors, it sends all routes it learned to those neighbors.
(d) When a node sends a routing update to its neighbors, it sends those routes it learned from each neighbor back to that neighbor with negative information (such as ∞).
(e) When a node sends a routing update to its neighbors, it sends all routes it learned to those neighbors with negative information (such as ∞)..
Internetworking19 https://www.youtube.com/watch?v=6fObMoU9-mg
7.24 Which of the following statements are correct for “Link State” routing protocol ? Assume that each node knows the cost of the link to each of its directly connected neighbors.
(a) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to all other nodes and distributes that vector to its immediate neighbors.
(b) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to all other nodes and distributes that vector to all other nodes.
(c) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to its immediate neighbors and distributes that vector to all other nodes.
(d) Each node constructs a one dimensional array (a vector) containing the “distances” (costs) to its immediate neighbors and distributes that vector to its immediate neighbors.
(e) The link state packets (LSP) are sent to all other nodes by using reliable flooding algorithm.
7.25 Which of the following statements are correct for “Open Shortest Path First (OSPF)” routing protocol ?
(a) It’s a Distance Vector based routing protocol
(b) It’s a Link State based routing protocol
(c) Each router computes its routing table directly from the LSP’s it has collected using the Dijkstra’s algorithm
(d) It finds the shortest path from the router to each other node
(e) It finds the shortest path from the each other node to the router.
Internetworking20 https://www.youtube.com/watch?v=1_07gjnWM0M
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