Q1. A network administrator executes the command clear ip route. Which two tables does this command clear and rebuild? (Choose two.)
A. IP routing
B. FIB
C. ARP cache
D. MAC address table
E. Cisco Express Forwarding table
F. topology table
Answer: A,B
Explanation:
To clear one or more entries in the IP routing table, use the following commands in any mode:
Command Purpose
clear ip route {* |
Clears one or more routes from both the
{route |
unicast RIB and all the module FIBs. The
prefix/length}[next-hop route options are as follows:
interface]}
· *--All routes.
[vrf vrf-name]
Example:
· route--An individual IP route.
switch(config)# clear ip
· prefix/length--Any IP prefix.
route
10.2.2.2 · next-hop--The next-hop address · interface--The interface to reach the next-hop address.
The vrf-name can be any case-sensitive, al-phanumeric string up to 32 characters.
Reference:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/unicast/5_0_3_N1_1/Ci
sco_n5k_layer3_ucast_cfg_rel_503_N1_1/l3_manage-routes.html
Q2. A network engineer has left a NetFlow capture enabled over the weekend to gather information regarding excessive bandwidth utilization. The following command is entered:
switch#show flow exporter Flow_Exporter-1 What is the expected output?
A. configuration of the specified flow exporter
B. current status of the specified flow exporter
C. status and statistics of the specified flow monitor
D. configuration of the specified flow monitor
Answer: B
Explanation:
show flow exporter exporter-name (Optional) Displays the current status of the specified flow exporter.
Example:
Device# show flow exporter
FLOW_EXPORTER-1
Reference: http://www.cisco.com/en/US/docs/ios-xml/ios/fnetflow/configuration/15-mt/cfg-de- fnflowexprts.
html
Q3. A network engineer is trying to implement broadcast-based NTP in a network and executes the ntp broadcast client command. Assuming that an NTP server is already set up, what is the result of the command?
A. It enables receiving NTP broadcasts on the interface where the command was executed.
B. It enables receiving NTP broadcasts on all interfaces globally.
C. It enables a device to be an NTP peer to another device.
D. It enables a device to receive NTP broadcast and unicast packets.
Answer: A
Explanation:
The NTP service can be activated by entering any ntp command. When you use the ntp broadcast client
command, the NTP service is activated (if it has not already been activated) and the device is configured to receive NTP broadcast packets on a specified interface simultaneously.
Command Description
ntp broadcast Allows the system to receive NTP broadcast packets on an client interface.
Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/bsm/command/bsm-xe-3se-3850- cr-book/
bsm-xe-3se-3850-cr-book_chapter_00.html
Q4. You have been asked to evaluate how EIGRP is functioning in a customer network.
What is the advertised distance for the 192.168.46.0 network on R1?
A. 333056
B. 1938688
C. 1810944
D. 307456
Answer: C
Explanation:
Q5. The enterprise network WAN link has been receiving several denial of service attacks from both IPv4 and IPv6 sources. Which three elements can you use to identify an IPv6 packet via its header, in order to filter future attacks? (Choose three.)
A. Traffic Class
B. Source address
C. Flow Label
D. Hop Limit
E. Destination Address
F. Fragment Offset
Answer: A,C,D
Explanation:
Q6. A network engineer executes the “ipv6 flowset” command. What is the result?
A. Flow-label marking in 1280-byte or larger packets is enabled.
B. Flow-set marking in 1280-byte or larger packets is enabled.
C. IPv6 PMTU is enabled on the router.
D. IPv6 flow control is enabled on the router.
Answer: A
Explanation:
Enabling Flow-Label Marking in Packets that Originate from the Device This feature allows the device to
track destinations to which the device has sent packets that
are 1280 bytes or larger.
SUMMARY STEPS
1.enable
2.configure terminal
3.ipv6 flowset
4.exit
5.clear ipv6 mtu
DETAILED STEPS
Command or Action Purpose
Step 1 enable Enables privileged EXEC mode.
Enter your password if prompted.
Example:
Device> enable
Step 2 configure terminal Enters global configuration mode.
Example:
Device# configure
terminal
Step 3 ipv6 flowset Configures flow-label marking in 1280-byte or larger packets sent by the device.
Example:
Device# configure
terminal
Step 3 ipv6 flowset Configures flow-label marking in 1280-byte or larger packets sent by the device.
Example:
Device(config)# ipv6
flowset
Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_basic/configuration/15- mt/ip6b-15-mtbook/ip6-mtu-path-disc.html
Q7. 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 192.1.1.20 192.1.1.254 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.
Answer: B
Explanation:
Q8. The following configuration is applied to a router at a branch site:
ipv6 dhcp pool dhcp-pool
dns-server 2001:DB8:1:B::1
dns-server 2001:DB8:3:307C::42
domain-name example.com
!
If IPv6 is configured with default settings on all interfaces on the router, which two dynamic IPv6 addressing mechanisms could you use on end hosts to provide end-to-end connectivity? (Choose two.)
A. EUI-64
B. SLAAC
C. DHCPv6
D. BOOTP
Answer: A,B
Explanation:
Q9. After you review the output of the command show ipv6 interface brief, you see that several IPv6 addresses have the 16-bit hexadecimal value of "FFFE" inserted into the address. Based on this information, what do you conclude about these IPv6 addresses?
A. IEEE EUI-64 was implemented when assigning IPv6 addresses on the device.
B. The addresses were misconfigured and will not function as intended.
C. IPv6 addresses containing "FFFE" indicate that the address is reserved for multicast.
D. The IPv6 universal/local flag (bit 7) was flipped.
E. IPv6 unicast forwarding was enabled, but IPv6 Cisco Express Forwarding was disabled.
Answer: A
Explanation:
Extended Unique Identifier (EUI), as per RFC2373, allows a host to assign iteslf a unique 64-
Bit IP Version 6 interface identifier (EUI-64). This feature is a key benefit over IPv4 as it eliminates the
need of manual configuration or DHCP as in the world of IPv4. The IPv6 EUI-64 format address is obtained
through the 48-bit MAC address. The Mac address is first separated into two 24-bits, with one being OUI
(Organizationally Unique Identifier) and the other being NIC specific. The 16-bit 0xFFFE is then inserted
between these two 24-bits to for the 64-bit EUI address. IEEE has chosen FFFE as a reserved value which
can only appear in EUI-64 generated from the an EUI-48 MAC address. Here is an example showing how
a the Mac Address is used to generate EUI.
Next, the seventh bit from the left, or the universal/local (U/L) bit, needs to be inverted. This bit identifies whether this interface identifier is universally or locally administered. If 0, the address is locally
administered and if 1, the address is globally unique. It is worth noticing that in the OUI portion, the globally
unique addresses assigned by the IEEE has always been set to 0 whereas the locally created addresses
has 1 configured. Therefore, when the bit is inverted, it maintains its original scope (global unique address
is still global unique and vice versa). The reason for inverting can be found in RFC4291 section 2.5.1.
Once the above is done, we have a fully functional EUI-64 format address.
Reference: https://
supportforums.cisco.com/document/100566/understanding-ipv6-eui-64-bit- address
Q10. Which three problems result from application mixing of UDP and TCP streams within a network with no QoS? (Choose three.)
A. starvation
B. jitter
C. latency
D. windowing
E. lower throughput
Answer: A,C,E
Explanation:
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
Q11. After a recent DoS attack on a network, senior management asks you to implement better logging functionality on all IOS-based devices. Which two actions can you take to provide enhanced logging results? (Choose two.)
A. Use the msec option to enable service time stamps.
B. Increase the logging history .
C. Set the logging severity level to 1.
D. Specify a logging rate limit.
E. Disable event logging on all noncritical items.
Answer: A,B
Explanation:
The optional msec keyword specifies the date/time format should include milliseconds. This can aid in
pinpointing the exact time of events, or to correlate the order that the events happened. To limit syslog messages sent to the router's history table and to an SNMP network management station based on severity, use the logging history command in global configuration mode. By default, Cisco devices Log error messages of severity levels 0 through 4 (emergency, alert, critical, error, and warning levels); in other words, "saving level warnings or higher." By increasing the severity level, more granular monitoring can occur, and SNMP messages will be sent by the less sever (5-7) messages.
Q12. Refer to the exhibit.
Which 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.
Answer: E
Explanation:
Q13. Scenario:
You have been asked to evaluate an OSPF network setup in a test lab and to answer questions a customer has about its operation. The customer has disabled your access to the show running-config command.
How many times was SPF algorithm executed on R4 for Area 1?
A. 1
B. 5
C. 9
D. 20
E. 54
F. 224
Answer: C
Explanation:
Q14. 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.
Answer: B
Explanation:
Q15. Which two actions must you perform to enable and use window scaling on a router? (Choose two.)
A. Execute the command ip tcp window-size 65536.
B. Set window scaling to be used on the remote host.
C. Execute the command ip tcp queuemax.
D. Set TCP options to "enabled" on the remote host.
E. Execute the command ip tcp adjust-mss.
Answer: A,B
Explanation:
The TCP Window Scaling feature adds support for the Window Scaling option in RFC 1323,
TCP Extensions for High Performance . A larger window size is recommended to improve TCP performance in network paths with large bandwidth-delay product characteristics that are called Long Fat
Networks (LFNs).
The TCP Window Scaling enhancement provides that support. The window scaling extension in Cisco IOS software expands the definition of the TCP window to 32 bits and then uses a scale factor to carry this 32-bit value in the 16-bit window field of the TCP header.
The window size can increase to a scale factor of 14. Typical applications use a scale factor of 3 when deployed in LFNs.
The TCP Window Scaling feature complies with RFC 1323. The larger scalable window size will allow TCP to perform better over LFNs.
Use the ip tcp window-size command in global configuration mode to configure the TCP window size. In order for this to work, the remote host must also support this feature and its window size must be increased.
Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipapp/
configuration/12-4t/iap-12- 4t-book/iap-tcp.html#GUID-BD998AC6-F128-47DD-B5F7-B226546D4B08
Q16. Which three characteristics are shared by subinterfaces and associated EVNs? (Choose three.)
A. IP address
B. routing table
C. forwarding table
D. access control lists
E. NetFlow configuration
Answer: A,B,C
Explanation:
A trunk interface can carry traffic for multiple EVNs. To simplify the configuration process, all
the subinterfaces and associated EVNs have the same IP address assigned. In other words, the trunk
interface is identified by the same IP address in different EVN contexts. This is accomplished as a result of
each EVN having a unique routing and forwarding table, thereby enabling support for overlapping IP
addresses across multiple EVNs. Reference: http://www.cisco.com/en/US/docs/ios-xml/ios/evn/
configuration/xe-3sg/evn- overview.pdf