cisco Q&A

01. Which OSI layer provides mechanical, electrical, procedural for activating, maintaining physical link?

A.) Presentation

B.) Network

C.)Application

D.) Physical

E.) Transport

F.)Data-Link

Answer: D

Explanation: Layer 1 the Physical layer performs this function.

202. Identify 2 characteristics of PPP?

A.) Uses LLC to establish the link

B.) Default serial encapsulation

C.) Support multiple layer 3 protocols

D.) Offers two types of authentication; PAP and CHAP

Answer: C D

Explanation: PPP is not the default encapsulation and uses LCP not LLC to establish the link.

It support multiple layer 3 protocols and supports authentication.

203. Identify 3 characteristics of a connection oriented protocol?

A.) Path determination

B.) Flow control

C.) Acknowledgements

D.) Uses hop count as metric

E.) 3 step handshake

Answer: B C E

Explanation: Connection oriented protocols must first establish the connection (3 step handshake), employ methods to acknowledge the receipt of data (acknowledgements) and slow down the flow of data if required (flow control).

204. What is the maximum hop count for IP RIP?

A.) Infinity

B.) 16

C.) 15

D.) 1

Answer:  C

Explanation: 15 is the maximum hop count, underscoring the size limitation of RIP.

205. What is Cisco’s default encapsulation method on serial interfaces?

A.) ANSI

B.) Cisco

C.) Q933a

D.) HDLC

Answer:  D

Explanation: Cisco’s implementation of HDLC is only compatible with Cisco routers. It is the default encapsulation type for serial interfaces.

206. Which of the following is a characteristic of a switch, but not of a repeater?

A.) Switches forward packets based on the IPX or IP address in the frame

B.) Switches forward packets based on the IP address in the frame

C.) Switches forward packets based on the MAC address in the frame

D.) Switches forward packets based only on the IP address in the packet

Answer: C A

Explanation: repeater regenerates the signal it receives, a switch makes decisions based upon MAC addresses to determine whether a frame should be forwarded. Repeaters forward all packets.

207. Ping uses which Internet layer protocol?

A.) RARP

B.) ICMP

C.) ARP

D.) FTP

Answer: B

Explanation: Internet Control Message Protocol – ICMP is a management protocol and messaging service provider for IP. Its messages are carried as IP datagrams. ICMP is used in the

following events: Destination Unreachable – If a router cannot send an IP packet any further, it uses an ICMP echo to send a message back to the sender notifying it that the remote node is

unreachable. Buffer Full – If a routers memory buffer is full ICMP will send out a message to the

originator. Hops – Each IP datagram is assigned a path. This consists of hops. If it goes through the maximum number of hops, the packet is discarded and the discarding router sends an ICMP

echo to the host. Ping – Ping use ICMP echo message to check connectivity.

208. Which is true regarding store-and-forward switching method?

A.) Latency varies depending on frame-length

B.) Latency is constant

C.) It is default for all Cisco switches

D.) It only reads the destination hardware address before forwarding the frame

Answer:  A

Explanation: Store-and-Forward switching copies the entire frame into its buffer and computes the CRC. If a CRC error is detected, the frame is discarded, or if the frame is a runt (less than 64 bytes including the CRC) or a giant (more than 1518 bytes including the CRC). The LAN switch then looks up the destination address in its switching table and determines the outgoing interface. The frame is then forwarded to the outgoing interface. Cisco Catalyst 5000 switches uses the Store-and-Forward method. The problem with Store-and-Forward switching is latency is increased. Latency also varies with the size of the frame. The larger the frame, the more latency associated. This of course is due to the fact that the entire frame is copied into its buffer before being forwarded.

209. Which three of the following are true statements about connection-oriented sessions?

A.) The segments delivered are acknowledged back to the sender upon their reception

B.)Any segments not acknowledged the are retransmitted by the receiver

C.) A manageable data flow is maintained in order to avoid congestion, overloading and loss of any data

D.) Segments are sequenced back into their proper order upon arrival at their destination

Answer:  A C D

Explanation: Connection-oriented services are useful for transmitting data from applications that are intolerant of delays and packet re-sequencing. FTP and Telnet applications are based on connection-oriented services as well as some voice and video programs. Any segment that is not acknowledged by the received is retransmitted by the sender.

210. What does a metric of 16 hops represent when using RIP?

A.) Number of hops to the destination

B.) Destination unreachable

C.) Number of routers

D.) Bandwidth

Answer:  B

Explanation: Routing Information Protocol (RIP) is a distance vector routing protocol that used hop count as its metric. The maximum hop count is 15, 16 hops is considered unreachable. RIP updates are broadcast every 30 seconds by default. RIP has an administrative distance of 120.

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