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28 Cards in this Set
- Front
- Back
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What four processes does the Network layer use to accomplish end-to-end transport?
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Addressing
Encapsulation Routing Decapsulation |
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What is a Network layer PDU called?
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Packet
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What are intermediary devices that connect different networks called?
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Routers
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The passage of a packet between two nodes is called?
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Hop
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Come common Network layer protocols include:
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Internet Protocol version 4 (IPv4)
Internet Protocol version 6 (IPv6) Novell Internetwork Packet Exchange (IPX) AppleTalk Connectionless Network Service (CLNS/DECNet) |
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IPv4 basic characteristics:
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* Connectionless - No connection is established before sending data packets.
* Best Effort (unreliable) - No overhead is used to guarantee packet delivery. * Media Independent - Operates independently of the medium carrying the data. |
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In a connectionless service, the sender doesn't know if:
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* the receiver is present
* the packet arrived * the receiver can read the packet |
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In a connectionless service, the receiver doesn't know:
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* when a packet is coming
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What does unreliable mean in terms of the IP?
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does not have the capability to manage, and recover from, undelivered or corrupt packets
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What does MTU stand for?
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Maximum Transmission Unit
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What is the role of MTU?
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Control data passed between Datalink and Network layer to determine the maximum packet size the media can handle
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What are the six key fields in the IP header?
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IP Source Address
IP Destination Address Time-to-Live (TTL) Type-of-Service (ToS) Protocol Fragment Offset |
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In the IP header, what function does TTL denote?
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Time to live. 8 bit binary value that indicates how many hops a packet can take before it "dies"
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In the IP header, what function does Protocol denote?
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8-bit binary value indicates the data payload type that the packet is carrying. The Protocol field enables the Network layer to pass the data to the appropriate upper-layer protocol, eg, UDP or TCP
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In the IP header, what function does ToS denote?
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The Type-of-Service field contains an 8-bit binary value that is used to determine the priority of each packet. This value enables a Quality-of-Service (QoS) mechanism to be applied to high priority packets
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In the IP header, what function does Fragment Offset denote?
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When fragmentation occurs, the IPv4 packet uses the Fragment Offset field and the MF flag in the IP header to reconstruct the packet when it arrives at the destination host
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What are the three main reasons for dividing a network?
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Geographic, purpose, ownership
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What are three common issues with large networks?
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Performance degradation
Security issues Address Management |
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What is a broadcast?
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a message sent from one host to all other hosts on the network.
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Dividing networks based on ownership means
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Dividing networks based on ownership means that access to and from resources outside each network can be prohibited, allowed, or monitored.
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What is a gateway?
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a router on a network that serves as an exit from that network
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What is the prefix length?
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The number of bits of an address used as the network portion
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Routes in a routing table have three main features:
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Destination network
Next-hop Metric |
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What is the address of the default route?
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0.0.0.0
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The default route is also known as the
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Gateway of Last Resort
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What Network layer problem is avoided or reduced by consistent end-to-end addressing?
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Reduces unnecessary broadcasts
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the IP address of the default gateway of a host can be viewed by issuing what commands?
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ipconfig or route print
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the routing table of a computer host can be examined at the command line by issuing what commands?
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netstat -r, route, or route PRINT
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