READ Free Dumps For Cisco- 400-101
| Question ID 18557 | Which three statements about Cisco HDLC are true? (Choose three.)
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| Option A | HDLC serial encapsulation provides asynchronous framing and error detection.
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| Option B | Serial link keepalives are maintained by SLARP.
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| Option C | HDLC serial encapsulation provides synchronous framing without retransmission.
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| Option D | HDLC frame size can be reduced with MPPC compression.
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| Option E | The interface is brought down after five ignored keepalives.
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| Option F | The interface is brought down after three ignored keepalives.
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| Correct Answer | B,C,F |
Explanation Explanation: Cisco High-Level Data Link Controller (HDLC) is the Cisco proprietary protocol for sending data over synchronous serial links using HDLC. Cisco HDLC also provides a simple control protocol called Serial Line Address Resolution Protocol (SLARP) to maintain serial link keepalives. For each encapsulation type, a certain number of keepalives ignored by a peer triggers the serial interface to transition to the down state. For HDLC encapsulation, three ignored keepalives causes the interface to be brought down. By default, synchronous serial lines use the High-Level Data Link Control (HDLC) serial encapsulation method, which provides the synchronous framing and error detection functions of HDLC without windowing or retransmission. Reference: http://www.cisco.com/c/en/us/td/docs/routers/access/800/819/software/configuration/Guide/ 819_SCG/6ser_conf.html#78662
| Question ID 18558 | Which statement is true regarding UDLD and STP timers?
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| Option A | The UDLD message timer should be two times the STP forward delay to prevent loops.
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| Option B | UDLD and STP are unrelated features, and there is no relation between the timers.
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| Option C | The timers need to be synced by using the spanning-tree udld-sync command.
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| Option D | The timers should be set in such a way that UDLD is detected before the STP forward delay expires.
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| Correct Answer | D |
Explanation Explanation: UDLD is designed to be a helper for STP. Therefore, UDLD should be able to detect an unidirectional link before STP would unblock the port due to missed BPDUs. Thus, when you configure UDLD timers, make sure your values are set so that unidirectional link is detected before STP MaxAge + 2xForwardDelay expires. Reference: http://blog.ine.com/tag/stp/