READ Free Dumps For Cisco- 400-101
| Question ID 18523 | What is the most efficient way to confirm whether microbursts of traffic are occurring?
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| Option A | Monitor the output traffic rate using the show interface command.
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| Option B | Monitor the output traffic rate using the show controllers command.
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| Option C | Check the CPU utilization of the router.
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| Option D | Sniff the traffic and plot the packet rate over time.
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| Correct Answer | D |
Explanation Explanation: Micro-bursting is a phenomenon where rapid bursts of data packets are sent in quick succession, leading to periods of full line-rate transmission that can overflow packet buffers of the network stack, both in network endpoints and routers and switches inside the network. In order to troubleshoot microbursts, you need a packet sniffer that can capture traffic over a long period of time and allow you to analyze it in the form of a graph which displays the saturation points (packet rate during microbursts versus total available bandwidth). You can eventually trace it to the source causing the bursts (e.g. stock trading applications). Reference: Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 989-994). Kindle Edition.
| Question ID 18524 | Which TCP feature allows a client to request a specific packet that was lost?
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| Option A | flow control
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| Option B | sliding window
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| Option C | fast recovery
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| Option D | selective acknowledgment
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| Correct Answer | D |
Explanation Explanation: ✑ TCP Selective Acknowledgment The TCP Selective Acknowledgment feature improves performance if multiple packets are lost from one TCP window of data. Prior to this feature, because of limited information available from cumulative acknowledgments, a TCP sender could learn about only one lost packet per-round-trip time. An aggressive sender could choose to resend packets early, but such re-sent segments might have already been successfully received. The TCP selective acknowledgment mechanism helps improve performance. The receiving TCP host returns selective acknowledgment packets to the sender, informing the sender of data that has been received. In other words, the receiver can acknowledge packets received out of order. The sender can then resend only missing data segments (instead of everything since the first missing packet). Prior to selective acknowledgment, if TCP lost packets 4 and 7 out of an 8-packet window, TCP would receive acknowledgment of only packets 1, 2, and 3. Packets 4 through 8 would need to be re-sent. With selective acknowledgment, TCP receives acknowledgment of packets 1, 2, 3, 5, 6, and 8. Only packets 4 and 7 must be re-sent. TCP selective acknowledgment is used only when multiple packets are dropped within one TCP window. There is no performance impact when the feature is enabled but not used. Use the ip tcp selective-ack command in global configuration mode to enable TCP selective acknowledgment. Refer to RFC 2018 for more details about TCP selective acknowledgment.