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Exam Code: 300-101 (Practice Exam Latest Test Questions VCE PDF)
Exam Name: Implementing Cisco IP Routing
Certification Provider: Cisco
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2016 May 300-101 Study Guide Questions:
Q18. Which common issue causes intermittent DMVPN tunnel flaps?
A. a routing neighbor reachability issue
B. a suboptimal routing table
C. interface bandwidth congestion
D. that the GRE tunnel to hub router is not encrypted
DMVPN Tunnel Flaps Intermittently Problem DMVPN tunnel flaps intermittently. Solution
When DMVPN tunnels flap, check the neighborship between the routers as issues with neighborship
formation between routers may cause the DMVPN tunnel to flap. In order to resolve this problem, make
sure the neighborship between the routers is always up. Reference: http://www.cisco.com/c/en/us/support/
Q19. Refer to the exhibit. The command is executed while configuring a point-to-multipoint Frame Relay interface. Which type of IPv6 address is portrayed in the exhibit?
Q20. Which three problems result from application mixing of UDP and TCP streams within a network with no QoS? (Choose three.)
E. lower throughput
It is a general best practice not to mix TCP-based traffic with UDP-based traffic (especially
streaming video) within a single service provider class due to the behaviors of these protocols during
periods of congestion. Specifically, TCP transmitters will throttle-back flows when drops have been
detected. Although some UDP applications have application-level windowing, flow control, and
retransmission capabilities, most UDP transmitters are completely oblivious to drops and thus never lower
transmission rates due to dropping. When TCP flows are combined with UDP flows in a single service
provider class and the class experiences congestion, then TCP flows will continually lower their rates,
potentially giving up their bandwidth to drop-oblivious UDP flows. This effect is called TCP-starvation/
UDP-dominance. This can increase latency and lower the overall throughput. TCP-starvation/UDPdominance
likely occurs if (TCP-based) mission-critical data is assigned to the same service provider class
as (UDP-based) streaming video and the class experiences sustained congestion. Even if WRED is
enabled on the service provider class, the same behavior would be observed, as WRED (for the most part)
only affects TCP-based flows. Granted, it is not always possible to separate TCP-based flows from UDPbased
flows, but it is beneficial to be aware of this behavior when making such application-mixing
decisions. Reference: http://www.cisco.com/warp/public/cc/so/neso/vpn/vpnsp/spqsd_wp.htm
Q21. A network administrator uses IP SLA to measure UDP performance and notices that packets on one router have a higher one-way delay compared to the opposite direction. Which UDP characteristic does this scenario describe?
C. connectionless communication
D. nonsequencing unordered packets
Cisco IOS IP SLAs provides a proactive notification feature with an SNMP trap. Each measurement
operation can monitor against a pre-set performance threshold.
Cisco IOS IP SLAs generates an SNMP trap to alert management applications if this threshold is crossed.
Several SNMP traps are available: round trip time, average jitter, one-way latency, jitter, packet loss, MOS, and connectivity tests.
Here is a partial sample output from the IP SLA statistics that can be seen:
router#show ip sla statistics 1
Round Trip Time (RTT) for Index 55
Latest RTT: 1 ms
Latest operation start time: *23:43:31.845 UTC Thu Feb 3 2005 Latest operation return code: OK
Number Of RTT: 10 RTT Min/Avg/Max: 1/1/1 milliseconds Latency one-way time:
Number of Latency one-way Samples: 0
Source to Destination Latency one way Min/Avg/Max: 0/0/0 milliseconds Destination to Source Latency
one way Min/Avg/Max: 0/0/0 milliseconds
Q22. To configure SNMPv3 implementation, a network engineer is using the AuthNoPriv security level. What effect does this action have on the SNMP messages?
A. They become unauthenticated and unencrypted.
B. They become authenticated and unencrypted.
C. They become authenticated and encrypted.
D. They become unauthenticated and encrypted.
Most up-to-date 300-101 exam answers:
Q23. Which three TCP enhancements can be used with TCP selective acknowledgments? (Choose three.)
A. header compression
B. explicit congestion notification
D. time stamps
E. TCP path discovery
F. MTU window
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
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
Refer to RFC 2018 for more details about TCP selective acknowledgment.
TCP Time Stamp
The TCP time-stamp option provides improved TCP round-trip time measurements. Because the time
stamps are always sent and echoed in both directions and the time-stamp value in the header is always
changing, TCP header compression will not compress the outgoing packet. To allow TCP header
compression over a serial link, the TCP time-stamp option is disabled. Use the ip tcp timestamp command
to enable the TCP time-stamp option.
TCP Explicit Congestion Notification
The TCP Explicit Congestion Notification (ECN) feature allows an intermediate router to notify end hosts of
impending network congestion. It also provides enhanced support for TCP sessions associated with
applications, such as Telnet, web browsing, and transfer of audio and video data that are sensitive to delay
or packet loss. The benefit of this feature is the reduction of delay and packet loss in data transmissions.
Use the ip tcp ecn command in global configuration mode to enable TCP ECN.
TCP Keepalive Timer
The TCP Keepalive Timer feature provides a mechanism to identify dead connections. When a TCP
connection on a routing device is idle for too long, the device sends a TCP keepalive packet to the peer
with only the Acknowledgment (ACK) flag turned on. If a response packet (a TCP ACK packet) is not
received after the device sends a specific number of probes, the connection is considered dead and the
device initiating the probes frees resources used by the TCP connection. Reference: http://www.cisco.com/
Q24. When using SNMPv3 with NoAuthNoPriv, which string is matched for authentication?
The following security models exist: SNMPv1, SNMPv2, SNMPv3. The following security
levels exits: "noAuthNoPriv" (no authentiation and no encryption noauth keyword in CLI),
"AuthNoPriv" (messages are authenticated but not encrypted auth keyword in CLI), "AuthPriv" (messages
are authenticated and encrypted priv keyword in CLI). SNMPv1 and SNMPv2 models only support the
"noAuthNoPriv" model since they use plain community string to match the incoming packets. The SNMPv3
implementations could be configured to use either of the models on per-group basis (in case if
"noAuthNoPriv" is configured, username serves as a replacement for community string). Reference: http://
Q25. Which type of BGP AS number is 64591?
A. a private AS number
B. a public AS number
C. a private 4-byte AS number
D. a public 4-byte AS number
Q26. PPPoE is composed of which two phases?
A. Active Authentication Phase and PPP Session Phase
B. Passive Discovery Phase and PPP Session Phase
C. Active Authorization Phase and PPP Session Phase
D. Active Discovery Phase and PPP Session Phase
PPPoE is composed of two main phases:
Active Discovery Phase--In this phase, the PPPoE client locates a PPPoE server, called an access
concentrator. During this phase, a Session ID is assigned and the PPPoE layer is established.
PPP Session Phase--In this phase, PPP options are negotiated and authentication is performed. Once the
link setup is completed, PPPoE functions as a Layer 2 encapsulation method, allowing data to be transferred over the PPP link within PPPoE headers.
Topic 3, Layer 3 Technologies
20. Refer to the exhibit.
Which one statement is true?
A. Traffic from the 172.16.0.0/16 network will be blocked by the ACL.
B. The 10.0.0.0/8 network will not be advertised by Router B because the network statement for the 10.0.0.0/8 network is missing from Router B.
C. The 10.0.0.0/8 network will not be in the routing table on Router B.
D. Users on the 10.0.0.0/8 network can successfully ping users on the 192.168.5.0/24 network, but users on the 192.168.5.0/24 cannot successfully ping users on the 10.0.0.0/8 network.
E. Router B will not advertise the 10.0.0.0/8 network because it is blocked by the ACL.
You can filter what individual routes are sent (out) or received (in) to any interface within your EIGRP
One example is noted above. If you filter outbound, the next neighbor(s) will not know about anything
except the 172.16.0.0/16 route and therefore won't send it to anyone else downstream. If you filter inbound, YOU won't know about the route and therefore won't send it to anyone else downstream.
Q27. You have been asked to evaluate how EIGRP is functioning in a customer network.
What percent of R1’s interfaces bandwidth is EIGRP allowed to use?
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Q28. Which NetFlow component is applied to an interface and collects information about flows?
A. flow monitor
B. flow exporter
C. flow sampler
D. flow collector
Flow monitors are the NetFlow component that is applied to interfaces to perform network
traffic monitoring. Flow monitors consist of a record and a cache. You add the record to the flow monitor
after you create the flow monitor. The flow monitor cache is automatically created at the time the flow
monitor is applied to the first interface. Flow data is collected from the network traffic during the monitoring
process based on the key and nonkey fields in the record, which is configured for the flow monitor and
stored in the flow monitor cache. Reference: http://www.cisco.com/c/en/us/td/docs/ios/fnetflow/command/
Q29. A network engineer is trying to modify an existing active NAT configuration on an IOS router by using the following command:
(config)# no ip nat pool dynamic-nat-pool 184.108.40.206 220.127.116.11 netmask 255.255.255.0
Upon entering the command on the IOS router, the following message is seen on the console:
%Dynamic Mapping in Use, Cannot remove message or the %Pool outpool in use, cannot destroy
What is the least impactful method that the engineer can use to modify the existing IP NAT configuration?
A. Clear the IP NAT translations using the clear ip nat traffic * " command, then replace the NAT configuration quickly, before any new NAT entries are populated into the translation table due to active NAT traffic.
B. Clear the IP NAT translations using the clear ip nat translation * " command, then replace the NAT configuration quickly, before any new NAT entries are populated into the translation table due to active NAT traffic.
C. Clear the IP NAT translations using the reload command on the router, then replace the NAT configuration quickly, before any new NAT entries are populated into the translation table due to active NAT traffic.
D. Clear the IP NAT translations using the clear ip nat table * " command, then replace the NAT configuration quickly, before any new NAT entries are populated into the translation table due to active NAT traffic.
Q30. A network engineer is investigating the cause of a service disruption on a network segment and executes the debug condition interface fastethernet f0/0 command. In which situation is the debugging output generated?
A. when packets on the interface are received and the interface is operational
B. when packets on the interface are received and logging buffered is enabled
C. when packets on the interface are received and forwarded to a configured syslog server
D. when packets on the interface are received and the interface is shut down
Q31. What are the three modes of Unicast Reverse Path Forwarding?
A. strict mode, loose mode, and VRF mode
B. strict mode, loose mode, and broadcast mode
C. strict mode, broadcast mode, and VRF mode
D. broadcast mode, loose mode, and VRF mode
Network administrators can use Unicast Reverse Path Forwarding (Unicast RPF) to help limit
the malicious traffic on an enterprise network. This security feature works by enabling a router to verify the
reachability of the source address in packets being forwarded. This capability can limit the appearance of
spoofed addresses on a network. If the source IP address is not valid, the packet is discarded. Unicast
RPF works in one of three different modes: strict mode, loose mode, or VRF mode. Note that not all
network devices support all three modes of operation. Unicast RPF in VRF mode will not be covered in this
document. When administrators use Unicast RPF in strict mode, the packet must be received on the
interface that the router would use to forward the return packet. Unicast RPF configured in strict mode may
drop legitimate traffic that is received on an interface that was not the router's choice for sending return
traffic. Dropping this legitimate traffic could occur when asymmetric routing paths are present in the
network. When administrators use Unicast RPF in loose mode, the source address must appear in the
routing table. Administrators can change this behavior using the allow-default option, which allows the use
of the default route in the source verification process. Additionally, a packet that contains a source address
for which the return route points to the Null 0 interface will be dropped. An access list may also be
specified that permits or denies certain source addresses in Unicast RPF loose mode. Care must be taken
to ensure that the appropriate Unicast RPF mode (loose or strict) is configured during the deployment of
this feature because it can drop legitimate traffic. Although asymmetric traffic flows may be of concern
when deploying this feature, Unicast RPF loose mode is a scalable option for networks that contain
asymmetric routing paths. Reference: http://www.cisco.com/web/about/security/intelligence/unicastrpf.
Q32. Which three benefits does the Cisco Easy Virtual Network provide to an enterprise network? (Choose three.)
A. simplified Layer 3 network virtualization
B. improved shared services support
C. enhanced management, troubleshooting, and usability
D. reduced configuration and deployment time for dot1q trunking
E. increased network performance and throughput
F. decreased BGP neighbor configurations
Q33. How does an IOS router process a packet that should be switched by Cisco Express Forwarding without an FIB entry?
A. by forwarding the packet
B. by dropping the packet
C. by creating a new FIB entry for the packet
D. by looking in the routing table for an alternate FIB entry
Q34. Refer to the following output:
Router#show ip nhrp detail
10.1.1.2/8 via 10.2.1.2, Tunnel1 created 00:00:12, expire 01:59:47
TypE. dynamic, Flags: authoritative unique nat registered used
NBMA address: 10.12.1.2
What does the authoritative flag mean in regards to the NHRP information?
A. It was obtained directly from the next-hop server.
B. Data packets are process switches for this mapping entry.
C. NHRP mapping is for networks that are local to this router.
D. The mapping entry was created in response to an NHRP registration request.
E. The NHRP mapping entry cannot be overwritten.
Show NHRP: Examples
The following is sample output from the show ip nhrp command:
Router# show ip nhrp
10.0.0.2 255.255.255.255, tunnel 100 created 0:00:43 expire 1:59:16 Type: dynamic Flags: authoritative
NBMA address: 10.1111.1111.1111.1111.1111.1111.1111.1111.1111.11 10.0.0.1 255.255.255.255,
Tunnel0 created 0:10:03 expire 1:49:56 Type: static Flags: authoritative NBMA address: 10.1.1.2 The
fields in the sample display are as follows:
The IP address and its network mask in the IP-to-NBMA address cache. The mask is always
255.255.255.255 because Cisco does not support aggregation of NBMA information through NHRP.
The interface type and number and how long ago it was created (hours:minutes:seconds).
The time in which the positive and negative authoritative NBMA address will expire
(hours:minutes:seconds). This value is based on the ip nhrp holdtime
Type of interface:
dynamic--NBMA address was obtained from the NHRP Request packet.
static--NBMA address was statically configured.
authoritative--Indicates that the NHRP information was obtained from the Next Hop Server or router that
maintains the NBMA-to-IP address mapping for a particular destination. Reference: http://www.cisco.com/
see more Implementing Cisco IP Routing