Cartes mémoires NRS-1 (Seite 4 von 6)

Cartes-fiches	215
Utilisateurs	11
Langue	English
Catégorie	Informatique
Niveau	Autres
Crée / Actualisé	01.05.2013 / 04.01.2019
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Which of the following best describes an autonomous system?

An autonomous system is a network or group of networks operating under one administrative authority

An autonomous system is another term for the collection of routers that make up the Internet

An autonomous system is a network or group of networks from many organizations running different IGP routing protocols, but all running BGP

An autonomous system is a loosely defined term that can refer to any organization that has a connection to the Internet

What are some of the characteristics of BGP? Choose three

BGP is an exterior gateway protocol

BGP routing is based on distance vector

BGP sends periodic updates to its neighbors

A router running BGP protocol needs an Autonomous system number

Which transport protocol and port number is used by BGP to establish and maintain a peering session with other BGP speakers?

TCP port 179

UDP port 179

TCP port 22

UDP port 22

Which of the following statements describes the purpose of the Transport Layer in the TCP/IP stack?

Provides a data transport service to higher protocol layers

Provides a data transport service for routing and control protocols such as OSPF and ICMP

Provides a universal address plan to uniquely identify every device in the network

Defines a standard method for framing data for transmission on the physical network medium

Which of the following is NOT a function of TCP?

Maintaining the ordering of data transmitted across the network

Ensuring the reliable transmission of data across the network

Providing the receiver with a flow control mechanism

Defining the method for routing data across the network

What must occur before two hosts can exchange data using TCP?

Nothing. The two hosts can send data to each other at any time

The two hosts must negotiate a path MTU to be used for the data exchange

The two hosts must perform a 3-way handshake before transmitting data

The two hosts must exchange encryption keys before transmitting data

Host A is transmitting data to host B on a TCP connection. What is the purpose of the ACK sent by host B?

The ACK tells the host A that host B wishes to establish a session

The ACK tells host A the sequence number of the segment that was just received by host B

The ACK tells host A the sequence number of the next segment that host B expects to see

The ACK is flow control from host B and tells host A to reduce its transmission rate

Host A receives a TCP SYN/ACK segment. What does this signify?

Host A has received a request to establish a TCP session

Host A has received a request to close a TCP session

A TCP session is now established to host A

The TCP session has been terminated due to a timeout

What is the purpose of the source and destination ports in the TCP header?

These ports identify the physical location of the sender and the receiver on the IP router

These ports are used as addresses to communicate with the IP layer

TCP does not use source or destination ports

These ports are used as an address to identify the upper layer application using the TCP connection

Which of the following is NOT a field in a TCP header?

Source port

MTU

Sequence number

Acknowledgement number

Window size

Which of the following fields is not a field in the TCP header used for the establishment and termination of a TCP connection?

TTL

ACK

FIN

SYN

The sequence numbers are used by TCP to ensure that the data receive is provided to the application in the correct order

TRUE

FALSE

What happens in a TCP session if a segment is not acknowledged within a certain time period?

The missing segment is retransmitted

The TCP session is terminated

The sender sends the next segment

An ICMP destination unreachable message is sent

What is the purpose of TCP flow control?

It restricts the sender from sending too much data when there is congestion in the network

It allows the receiver to control the rate at which the sender transmits data

It forces the sender to send only one segment at a time

It allows the receiver to drop segments without the sender having to retransmit

Which field in the TCP header is used by the receiver to indicate how many segments it can receive?

Checksum

SYN

Destination port

Window size

MTU

What must the sender do when it receives a window size of 0 from the receiver?

Stop transmitting

Terminate the TCP session

Send the next segment

Retransmit the previous segment

Which of the following statements BEST describes the purpose of UDP (Select two)?

Provide a connectionless delivery service

Provide a connection oriented delivery service

Provide an unreliable transmission service

Provide a reliable transmission service

Why does UDP have less overhead then TCP?

UDP has less overhead because it is only used for transmission of small amounts of data

UDP has less overhead then TCP because there is no checksum field in UDP

UDP overhead is the same as TCP because it uses the same fields in the header

UDP has less overhead because there is no requirement for acknowledgment or retransmission

Which application below would be likely to use UDP?

Real-time audio application such as VoIP

Web browser

Email application

Telnet

How does the Transport Layer identify which application is to receive the data?

Using the IP address of the packet

Using the MAC address of the frame

Using port numbers

Using Connection Identifier Numbers (CIN)

What capability of TCP/IP allows two hosts to have multiple TCP sessions to each other simultaneously?

The combination of IP source and destination address and TCP source and destination port uniquely identifies each session

The combination of IP source and destination address and the IP protocol field uniquely identifies each session

The hosts can identify the sessions using each others MAC addresses

Two hosts can not have multiple TCP sessions simultaneously

What operation is performed by an LSR when it receives an MPLS labeled packet?

The LSR refers to its routing table and forwards the packet to the next LSR or LER without altering the MPLS label

The LSR refers to its MPLS label table, swaps the label and forwards the packet to the next LSR or LER

The LSR refers to its MPLS label table forwards the packet to the next LSR or LER without altering the MPLS label

The LSR refers to its MPLS label table, pops the label and forwards the packet to the next IP router

What is the function of an LSR?

Label Switching Routers make switching decisions based on the original MAC Header

Label Switching Routers make routing decisions based on the original IP Header

Label Switching Routers make forwarding decisions based on the MPLS label

Label Switching Routers make decisions based on ATM header information

In an MPLS network, which device is responsible for taking an unlabeled packet and encapsulating it with an MPLS label?

Ingress Label Edge Router

Egress Label Edge Router

Label Switching Router

Next Hop Router

Which device is responsible for removing the MPLS label before the packet reaches the CE device?

The CE device removes the MPLS label

The last LSR on the LSP removes the MPLS label

MPLS labels are not removed until they reach the final destination

The egress LER removes the MPLS label

A CE device has a physical connection to which device in the service providers MPLS network?

CE always connects to a PE router

CE always connects to a P router

CE always connects to another CE device

The CE does not connect to the service provider network

Which of the following are correct statements about MPLS labels (Choose three)?

A series of labels from one LER to another LER represent a logical tunnel known as an LSP

Labels used for a LSP may be static but are usually signaled dynamically with an MPLS label signaling protocol

Labels are locally significant to the MPLS router which means its possible for two routers on the LSP path to use the same label

Labels are globally significant to the MPLS network which means all labels on the LSP path must be unique

Labels used for an LSP must be statically assigned by the service provider

How does LDP select the path used for an LSP?

LDP monitors the available bandwidth on all links and signals the LSP based on this information

LDP uses the shortest hop-count between two endpoints for the LSP

LDP must be configured hop-by-hop by the service provider

LDP follows the path chosen by the IGP

Which two protocols are used for the dynamic signaling of MPLS labels (Choose two)?

RSVP-TE

CSPF

PNNI

LDP

Which of the following are accurate statements about the PE device in a service providers MPLS network? (Select three)

A PE router only connects to CE devices

A PE router only connects to P routers

A PE router connects to at least one P router

A PE router connects to at least one CE device

PE routers support many different interface types connecting to CE devices

Where would you expect to find a P router in a service provider s network?

At the edge of the provider s network facing the customer

At the edge of the customer s network facing the provider

In the core of the providers network

On the customer premises

Which of the following are considered Virtual Private Networks? Choose all that apply

IES

VPWS

VPLS

VPRN

Which of the following are NOT examples of a VPN service offered on the Alcatel-Lucent 7750 SR? Choose two

VPWS Virtual Private Wire Service

VPLS Virtual Private LAN Service

VPRN Virtual Private Routed Networks

MLPPP Multi-link Point-to-Point protocol

VPDFS Virtual Private Dark Fiber Service

Which statement best describes a SAP?

The Service ATM Point is used for ATM connections to a PE

The Service Access Point is defined on the PE device and is the customers access to the service

The Service Access Point is defined on the P device and is the customers access to the service

The Service Access Point is defined on the CE device and is the customers access to the service

Multiple SAPs may be defined on the same physical port and may be used for different services

True

False

SAPs may be a port, a port with a specific VLAN tag in the case of an Ethernet port, or a port with a specific Circuit ID in the case of ATM or Frame Relay

True

False

Which statement best describes an SDP?

Service Delivery Points are defined on the service provider network side and used to bind the service to an MPLS transport tunnel. Many services can be bound to a single SDP

Service Delivery Points are defined on the service provider access side and used to bind the connection of the service to CE device. Many services can be bound to a single SDP

Service Delivery Points are defined on the service provider network side and used to bind the service to an MPLS transport tunnel. Only one service can be bound to a single SDP

Service Delivery Points are defined on the service provider access side and used to bind the service to CE device. Only one service can be bound to a single SDP

Which statement best describes a VPRN service?

From the customers perspective it looks as if all sites are connected by the same set of dark fibers

From the customers perspective it looks as if all sites are connected to a private switched network administered by the service provider

From the customers perspective it looks as if all sites are connected to a private routed network administered by the service provider

From the customers perspective it looks as if all sites have public internet access administered by the service provider

How does a VPRN service avoid the problem overlapping IP addresses from different customers?

You cannot have overlapping IP addresses. The service provider must ensure that its customers are all using discrete IP address space

Each VPRN service maintains a separate VPN routing and forwarding instance to separate customer routing information

A VPRN will ignore IP addressing information and use MAC addressing instead which are always unique

A VPRN will translate customer IP addresses to a private addressing scheme administered by the service provider

How does a VPRN service avoid the problem of overlapping IP addresses from different customers?

You cannot have overlapping IP addresses. Customers must change their IP address assignment

Each VPRN service maintains a separate VPN routing and forwarding instance to separate customer routing information. This allows for overlapping addresses

A VPRN ignores IP addressing information and uses MAC addressing instead, which are always unique

A VPRN translates customer IP addresses to a private addressing scheme administered by the service provider

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