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Final Exam
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Perguntas do quiz (81)
1The receiving side encapsulates segments
into datagrams.- AVerdadeiro
- BFalso
2The receiving side delivers
segments to the transport
layer.- AVerdadeiro
- BFalso
3Network layer protocols
are in- Amost hosts, but all routers
- Bevery host, router
- Cnot in routers but in end systems
- Dedge routers between ISPs
4A router examines header
fields in all IP datagrams
passing through it.- AVerdadeiro
- BFalso
5Network-layer functions:
- Aforwarding: move packets
from router’s input to
appropriate router output - Brouting: multiplexing and
demultiplexing - Crouting: determine route
taken by packets from
source to destination - Dforwarding: use header info to deliver
received segments to correct
socket
- Aforwarding: move packets
6Traditional routing algorithms on a Per-router control plane:
Routing algorithm components can be (are almost always) different in each and every router within the control plane.- AVerdadeiro
- BFalso
7Software-defined networking
(SDN): implemented in
(remote) servers:
Logically centralized control plane
A distinct (typically remote) controller interacts with local
control agents (CAs)- AVerdadeiro
- BFalso
8DCHP does not stand for Dynamic Host Configuration Protocol.
- AVerdadeiro
- BFalso
9Physical network ports are the same ports as in the transport layer.
- AVerdadeiro
- BFalso
10Transport layer uses software ports which are different from the physical ports of the network layer.
- AVerdadeiro
- BFalso
11IP headers include:
- Asource IP address
- Bdestination IP address
- Cmulti-hop router addresses
- DMAC address of the source
- Emetadata needed to route and deliver the datagram
12DHCP (Dynamic Host Configuration Protocol) uses:
- AUDP
- BTCP
- CIP
- DMX
- EDASH
13A DHCP (Dynamic Host Configuration Protocol) server enables computers to request IP addresses and networking parameters automatically from the Internet service provider (ISP).
- AVerdadeiro
- BFalso
14IP Broadcast:
- ARequest for IP address is broadcast
- BResponse for IP address is broadcast
- CResponse for IP address is unicast
- DRequest for IP address is unicast
15The types of switching fabrics:
- Amemory
- Bstorage
- Cbus
- Dcrossbar
- Ebuffer
16Switching rate: rate at which packets can be
transferred from inputs to outputs- AVerdadeiro
- BFalso
17What do Switching Fabrics do?
- Atransfer packet from input buffer to appropriate
output buffer - Btransfer datagrams from transport layer to network layer
- Csend frames between access points
- Atransfer packet from input buffer to appropriate
18Devices within a subnet can't physically reach
each other without an
intervening router.- AVerdadeiro
- BFalso
19Different subnets require a router to reach each other.
- AVerdadeiro
- BFalso
20An isolated network is called a:
- Asubnet
- Baccess point
- Cgateway
- Dedge system
21CIDR: Classless InterDomain Routing
What part of an address is the number of bits for the subnet portion of an address, when the address format is "a.b.c.d/x"?- Ad
- Bb
- Cc.d
- Dx
22DHCP: Dynamic Host Configuration Protocol
When an host dynamically obtains its IP address from the network sever is keeps that address and stores it in memory.- AVerdadeiro
- BFalso
23DCHP can return more than just allocated IP address on a subnet.
- AVerdadeiro
- BFalso
24DHCP can return:
- Aaddress of first-hop router for client
- Bname and IP address of DNS sever
- Cnetwork mask (indicating network versus host portion
of address) - DIP address for host
- Ename and IP address of MAC
- Faddress of lost-hop router for client
25NAT stands for Network Address Translation
- AVerdadeiro
- BFalso
26NAT: Local network uses different IP addresses for each device as far as outside wold is concerned.
- AVerdadeiro
- BFalso
27NAT: network address translation
- ARange of addresses is needed from ISP:
IP addresses for all devices - BRange of addresses not needed from ISP: just one
IP address for all devices - CCan change ISP without changing addresses of
devices in local network - Ddevices inside local net not explicitly addressable,
visible by outside world (a security plus)
- ARange of addresses is needed from ISP:
28WAN stands for wide area network and LAN stands for Local Area Network
- AVerdadeiro
- BFalso
29IPv6 motivation:
- A32-bit address space soon to be
completely allocated. 128 bit addresses (16 bytes) in IPv6 - Bheader format helps speed up
processing/forwarding
• fixed-length 40 byte header
• no fragmentation allowed
• checksum removed entirely to reduce processing time at
each hop - C32-bit address space soon to be
completely allocated. 64 bit addresses (16 bytes) in IPv6 - Dheader format helps speed up
processing/forwarding
• fixed-length 32 byte header
• no fragmentation allowed
• checksum removed entirely to reduce processing time at
each hop
- A32-bit address space soon to be
30IP datagrams have only the destination IP address
- AVerdadeiro
- BFalso
31Tunneling: An IPv6 datagram can be carried as a payload in an IPv4 datagram on IPv4 routers.
- AVerdadeiro
- BFalso
32A logically centralized (SDN) routing controller distributes:
- Aforwarding table
- Bflow table: headers, counters, actions
- Creturn table
33Network layer functions:
forwarding: move packets
from router’s input to
appropriate router output
data plane- AVerdadeiro
- BFalso
34Network layer functions:
routing: determine route
taken by packets from source
to destination
control plane- AVerdadeiro
- BFalso
35A sequence of routers' packets will traverse in
going from a given initial source host to a given final
destination host. This is called:- Apath
- Bnetwork
- Cgraph
- Dvector
36 Global or decentralized?
- A“link state” algorithms: all routers have complete
topology, link cost info - BDijkstra's algorithm: all routers have complete
topology, link cost info - C“distance vector” algorithms: all routers have complete
topology, link cost info - D“distance vector” algorithms: router knows physically-connected neighbors, link
costs to neighbors - E“distance vector” algorithms: iterative process of
computation, exchange of
info with neighbors - FDijkstra's algorithm: iterative process of
computation, exchange of
info with neighbors
- A“link state” algorithms: all routers have complete
37Dijkstra's algorithm is n(n+1)/2 comparisons: O(n^2)
- AVerdadeiro
- BFalso
38Distance vector algorithm: If any router notices link cost change:
- AOnly the routers noticing the change recompute.
- BAll routers recompute.
- COnly the changed router(s) recompute.
39Distance vector algorithm can result in transient loops because all routers try to recompute distance and incorrectly update and get stuck "correcting".
- AVerdadeiro
- BFalso
40Dijkstra's algorithm can result in transient loops because all routers try to recompute distance and incorrectly update and get stuck "correcting".
- AVerdadeiro
- BFalso
41Distance vector alogrithm:
Constantly, each node sends its own
distance vector estimate to neighbors- AVerdadeiro
- BFalso
42Distance vector algorithm each node notifies
neighbors when its
DVis not changing.- AVerdadeiro
- BFalso
43DV:
- Aeach node computes only its
own table - Beach node’s table used by
others
- Aeach node computes only its
44AS does not stand for Autonomous System.
- AVerdadeiro
- BFalso
45All routers in the world must run
same intra-domain protocol.- AVerdadeiro
- BFalso
46Intra-AS means between AS's.
- AVerdadeiro
- BFalso
47Which of these are Inter-AS protocols?
- ARIP
- BIGRP
- COSPF
- DBGP
48Output port Buffering on a router:
How much buffering is the rule of thumb?- ARTT(typical)*C(link capacity)
- BRTT*2
- CW*2
- Dprocessing time + forwarding time
49What happens when a large IP datagram gets "fragmented" (divided) within a net?
- Aone datagram becomes
several datagrams - Bthe datagram is corrupted and loss occurs
- C“reassembled” only at
final destination - DIP header bits used to
identify, order related
fragments - ETransport header is used to determine source port
- F“reassembled” at each switch or connected router
- Aone datagram becomes
50A router is designed as:
- Aswitching fabrics, input ports, output ports
- Binput ports, switching fabrics, output ports
- Cswitching fabrics, input ports, output ports, switching fabrics
- Dinput ports, output ports
- Einput ports, switching fabrics, output ports on the forwarding data plane and a routing processor on control plane.
51What does CIDR stand for?
- AClassless InterDomain Routing
- BConfiguration InterDomain Routing
- CClassless InterDomain Ranging
52What is the router located at the "edge" of its own AS, with links to a router or routers in other AS'es called?
- AGateway router
- BEdge router
- CEdge system
- Dinter router
53Forwarding tables are configured by both intra and inter AS routing algorithms.
- AVerdadeiro
- BFalso
54Intra-AS forwarding tables determine entries for
external destinations.- AVerdadeiro
- BFalso
55IGP and BGP stand for:
- Ainterior gateway protocol and border gateway protocol
- Binside group protocol and border gateway protocol
- Cinter gateway protocol and beyond gateway protocol
56A home network is an AS.
- AVerdadeiro
- BFalso
57Common intra-AS routing protocols:
- ARIP
- BIGRP
- COSPF
- DBGP
- EIP
- FTCP
- GIRYP
58OSPF (Open Shortest Path First) intra-AS routing protocol uses Dijkstra's algorithm, therefore a topology map is at each node.
- AVerdadeiro
- BFalso
59OSPF routers flood OSPF link-state advertisements to all other routers in entire AS.
- AVerdadeiro
- BFalso
60BGP (Border Gateway Protocol):
- Aintra-domain
- Binter-domain
- COnly tells you which AS to go through and nothing actually about the
AS - Dallows subnet to advertise its existence to the rest of the Internet
- Epropagate reachability information to all AS internal routers
61The protocol that makes the internet possible is:
- ABGP
- BIP
- CTCP
- DOSPF
62BGP has two important attributes:
• AS-PATH: list of AS'es through which prefix advertisement
has passed
• NEXT-HOP: gateway router that advertised the route- AVerdadeiro
- BFalso
63BGP messages use:
- ATCP
- BUDP
- COSPF
64Host and routers use ICMP (Internet Control Message Protocol) to communicate network-level information. ICMP messages are carried in IP datagrams to notify of some type of networking error or something similar.
- AVerdadeiro
- BFalso
65Link layer uses hosts and routers which are known as nodes.
- AVerdadeiro
- BFalso
66Link layer distinguishes between end systems, hosts, or routers.
- AVerdadeiro
- BFalso
67A frame is added to a datagram which encapsulates the datagram.
- AVerdadeiro
- BFalso
68End-to-end reliability (TCP) is not required because the link layer provides reliability between adjacent nodes.
- AVerdadeiro
- BFalso
69Link Layer services:
- Aflow control
- Berror detection
- Cerror correction
- Dhalf-duplex and full-duplex
- Eend-to-end reliability
- Fstore-and-forward
70half-duplex vs. full-duplex: with half-duplex, nodes at both ends of link can transmit, but not at the same time.
- AVerdadeiro
- BFalso
71Where is the link layer implemented?
- Ain each and every node
- Blink layer implemented in network adapter (aka network interface card NIC) or on a chip
- Cabove transport layer
- Dbeside the switching fabrics
- Ein memory
72Parity checking:
single bit parity: detect single bit errors
two-dimensional bit parity: detect and correct single bit errors- AVerdadeiro
- BFalso
73If MAC address of frame is unknown for destination of a frame:
- Abroadcast (flood) the frame to all nodes (except the one which sent the frame. Once the destination is known, use selective forward instead of flood.
- Bdrop the frame, wait for one with a known destination
74MAC address used for link-layer broadcast is:
- AFF-FF-FF-FF-FF-FF
- B0-0-0-0-0-0
- C256-256-256-256-256-256
- D00-00-00-00-00-00
75Switches must be connected in tree topology.
- AVerdadeiro
- BFalso
76Switches can connect different subnets together.
- AVerdadeiro
- BFalso
77Slotted ALOHA
- AIf you have a packet to send you must wait until the beginning of the time slot to send it
- Befficiency=P_success
- Ctput=P_success*R (R is channel capacity)
- DAll connected nodes get different tput
- EMaximum performance of an optimized system is 37%
78Pure (unslotted) ALOHA
- AWhen frame first arrives, transmit immediately
- Bwait for open slot
- Ccollision probability increase due to no synchronization
- D18% efficient
- E37% efficient
79CSMA (carrier sense multiple access):
if channel busy: transmit entire frame- AVerdadeiro
- BFalso
80CSMA/CD: efficiency=DataTrans/(DataTrans+Collision)
- AVerdadeiro
- BFalso
81CSMA/CD (collision detection) has 50% chance of success in first retry for 2 nodes.
- AVerdadeiro
- BFalso
Informações
- Descrição
- Quiz sobre Final Exam, criado por Connor Britton em 21-04-2019.
- Autor
- Connor Britton
- Idioma
- English
- Visualizações
- 1
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