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Q1. Refer to the exhibit.
Which two pieces of information in this Wireshark capture indicate that you are viewing EIGRP traffic? (Choose two.)
A. the header length
B. the protocol number
C. the destination address
D. the Class Selector
E. the source address
F. the header checksum
Answer: B,C
Explanation:
EIGRP uses protocol number 88, which shows as EIGRP in the capture. Also, we in the capture that the destination IP address is 224.0.0.10, which is the Enhanced Interior Gateway Routing Protocol (EIGRP) group address is used to send routing information to all EIGRP routers on a network segment.
Q2. Refer to the exhibit.
What is the role of this multicast router?
A. a first-hop PIM router
B. a last-hop PIM router
C. a PIM rendezvous point
D. a PIM inter-AS router
Answer: C
Explanation:
The following is sample output from the show ip pim tunnel taken from an RP. The output is used to verify the PIM Encap and Decap Tunnel on the RP:
Switch# show ip pim tunnel
Tunnel0
Type : PIM Encap
RP : 70.70.70.1*
SourcE. 70.70.70.1
Tunnel1*
Type : PIM Decap
RP : 70.70.70.1*
SourcE. -R2#
The asterisk (*) indicates that the router is the RP. The RP will always have a PIM Encap and Decap Tunnel interface.
Reference:
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/software/release/3se/multic ast/command_reference/b_mc_3se_3650_cr/b_mc_3se_3650_cr_chapter_010.html#wp12 86920037
Q3. Which two statements about the BGP community attribute are true? (Choose two.)
A. Routers send the community attribute to all BGP neighbors automatically.
B. A router can change a received community attribute before advertising it to peers.
C. It is a well-known, discretionary BGP attribute.
D. It is an optional transitive BGP attribute.
E. A prefix can support only one community attribute.
Answer: B,D
Explanation:
A community is a group of prefixes that share some common property and can be configured with the BGP community attribute. The BGP Community attribute is an optional transitive attribute of variable length. The attribute consists of a set of four octet values that specify a community. The community attribute values are encoded with an Autonomous System (AS) number in the first two octets, with the remaining two octets defined by the AS. A prefix can have more than one community attribute. A BGP speaker that sees multiple community attributes in a prefix can act based on one, some or all the attributes. A router has the option to add or modify a community attribute before the router passes the attribute on to other peers.
Reference:
http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/28784-bgp-community.html
Q4. Which three EIGRP packet types are valid? (Choose three.)
A. open
B. notification
C. keep-alive
D. hello
E. query
F. reply
Answer: D,E,F
Explanation:
EIGRP uses the following packet types: hello and acknowledgment, update, and query and reply.
Hello packets are multicast for neighbor discovery/recovery and do not require acknowledgment. An acknowledgment packet is a hello packet that has no data. Acknowledgment packets contain a nonzero acknowledgment number and always are sent by using a unicast address.
Update packets are used to convey reachability of destinations. When a new neighbor is discovered, unicast update packets are sent so that the neighbor can build up its topology table. In other cases, such as a link-cost change, updates are multicast. Updates always are transmitted reliably.
Query and reply packets are sent when a destination has no feasible successors. Query packets are always multicast. Reply packets are sent in response to query packets to instruct the originator not to recompute the route because feasible successors exist. Reply packets are unicast to the originator of the query. Both query and reply packets are transmitted reliably.
Reference: http://docwiki.cisco.com/wiki/Enhanced_Interior_Gateway_Routing_Protocol
Q5. DRAG DROP
Drag and drop the EIGRP term on the left to the corresponding definition on the right.
Answer:
Q6. Refer to the exhibit.
Assuming that the peer is configured correctly and the interface is up, how many neighbors will be seen in the EIGRPv6 neighbor table on this IPv6-only router?
A. one neighbor, which will use a local router-id of 6010. AB8. . /64
B. one neighbor, which will use a local router-id of 6020. AB8. . /64
C. none, because EIGRPv6 only supports authenticated peers
D. none, because of the mismatch of timers
E. none, because there is no EIGRP router ID configured
Answer: E
Explanation:
Configuring EIGRP for IPv6 has some restrictions; they are listed below:
. The interfaces can be directly configured with EIGRP for IPv6, without the use of a global IPv6 address. There is no network statement in EIGRP for IPv6.
. The router ID needs to be configured for an EIGRPv6 protocol instance before it can run.
. EIGRP for IPv6 has a shutdown feature. Ensure that the routing process is in "no shut" mode to start running the protocol.
Reference: http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/113267-eigrp-ipv6-00.html
Q7. Which statement about the feasible distance in EIGRP is true?
A. It is the maximum metric that should feasibly be considered for installation in the RIB.
B. It is the minimum metric to reach the destination as stored in the topology table.
C. It is the metric that is supplied by the best next hop toward the destination.
D. It is the maximum metric possible based on the maximum hop count that is allowed.
Answer: B
Explanation:
An EIGRP router advertises each destination it can reach as a route with an attached metric. This metric is called the route's reported distance (the term advertised distance has also been used in older documentation). A successor route for any given destination is chosen as having the lowest computed feasible distance; that is, the lowest sum of reported distance plus the cost to get to the advertising router. By default, an EIGRP router will store only the route with the best (lowest) feasible distance in the routing table (or, multiple routes with equivalent feasible distances).
Reference: http://packetlife.net/blog/2010/aug/9/eigrp-feasible-successor-routes/
Q8. DRAG DROP
Drag and drop the OSPF network type on the left to the correct category of timers on the right.
Answer:
Q9. Which two features improve BGP convergence? (Choose two.)
A. next-hop address tracking
B. additional paths
C. advertise map
D. communities
E. soft reconfiguration
Answer: A,B
Explanation:
The BGP Support for Next-Hop Address Tracking feature is enabled by default when a supporting Cisco software image is installed. BGP next-hop address tracking is event driven. BGP prefixes are automatically tracked as peering sessions are established. Next-hop changes are rapidly reported to the BGP routing process as they are updated in the RIB. This optimization improves overall BGP convergence by reducing the response time to next-hop changes for routes installed in the RIB. When a best path calculation is run in between BGP scanner cycles, only next-hop changes are tracked and processed. BGP routers and route reflectors (RRs) propagate only their best path over their sessions. The advertisement of a prefix replaces the previous announcement of that prefix (this behavior is known as an implicit withdraw). The implicit withdraw can achieve better scaling, but at the cost of path diversity. Path hiding can prevent efficient use of BGP multipath, prevent hitless planned maintenance, and can lead to MED oscillations and suboptimal hot-potato routing. Upon nexthop failures, path hiding also inhibits fast and local recovery because the network has to wait for BGP control plane convergence to restore traffic. The BGP Additional Paths feature provides a generic way of offering path diversity; the Best External or Best Internal features offer path diversity only in limited scenarios. The BGP Additional Paths feature provides a way for multiple paths for the same prefix to be advertised without the new paths implicitly replacing the previous paths. Thus, path diversity is achieved instead of path hiding.
References: http://www.cisco.com/en/US/docs/ios-xml/ios/iproute_bgp/configuration/15-1sg/irg-nexthop-track.html http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-3s/irg-xe-3s-book/bgp_additional_paths.html
Q10. Which protocol is the encapsulating protocol for mtrace packets?
A. ICMP
B. IGMP
C. PIM
D. GRE
Answer: B
Explanation:
“mtrace” is a diagnostic tool to trace the multicast path from a specified source to a destination for a multicast group. It runs over IGMP protocol. Mtrace uses any information available to it to determine a previous hop to forward the trace towards the source.
Reference: http://www.brocade.com/downloads/documents/html_product_manuals/NI_05500c_MULTI CAST/wwhelp/wwhimpl/common/html/wwhelp.htm#context=NI_MCAST&file=IP_Multicast. 3.04.html
Q11. Which option is the default maximum age of the MAC address table?
A. 300 seconds
B. 500 seconds
C. 1200 seconds
D. 3600 seconds
Answer: A
Explanation:
To configure the maximum aging time for entries in the Layer 2 table, use the mac-address-table aging-time command in global configuration mode.
Syntax Description
seconds
MAC address table entry maximum age. Valid values are 0, and from 5 to 1000000 seconds. Aging time is counted from the last time that the switch detected the MAC address. The default value is 300 seconds.
Reference: http://www.cisco.com/c/en/us/td/docs/ios/lanswitch/command/reference/lsw_book/lsw_m1. html
Q12. Refer to the exhibit.
What kind of load balancing is done on this router?
A. per-packet load balancing
B. per-flow load balancing
C. per-label load balancing
D. star round-robin load balancing
Answer: A
Explanation:
Here we can see that for the same traffic source/destination pair of 10.0.0.1 to 14.0.0.2 there were a total of 100 packets (shown by second entry without the *) and that the packets were distributed evenly across the three different outgoing interfaces (34, 33, 33 packets, respectively.
Q13. Which two statements about HSRP are true? (Choose two.)
A. Its virtual MAC is 0000.0C07.Acxx.
B. Its multicast virtual MAC is 0000.5E00.01xx.
C. Its default configuration allows for pre-emption.
D. It supports tracking.
E. It supports unique virtual MAC addresses.
Answer: A,D
Explanation:
Default HSRP Configuration
Feature
Default Setting
HSRP version
Version 1
HSRP groups
None configured
Standby group number
0
Standby MAC address
System assigned as: 0000.0c07.acXX, where XX is the HSRP group number
Standby priority
100
Standby delay
0 (no delay)
Standby track interface priority
10
Standby hello time
3 seconds
Standby holdtime
10 seconds
. The standby track interface configuration command ties the router hot standby priority to the availability of its interfaces and is useful for tracking interfaces that are not configured for HSRP. When a tracked interface fails, the hot standby priority on the device on which tracking has been configured decreases by 10. If an interface is not tracked, its state changes do not affect the hot standby priority of the configured device. For each interface configured for hot standby, you can configure a separate list of interfaces to be tracked.
. The standby track interface-priority interface configuration command specifies how much to decrement the hot standby priority when a tracked interface goes down. When the interface comes back up, the priority is incremented by the same amount.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/1 2-2_55_se/configuration/guide/3750xscg/swhsrp.html
Q14. Refer to the exhibit.
If you change the Spanning Tree Protocol from pvst to rapid-pvst, what is the effect on the interface Fa0/1 port state?
A. It transitions to the listening state, and then the forwarding state.
B. It transitions to the learning state and then the forwarding state.
C. It transitions to the blocking state, then the learning state, and then the forwarding state.
D. It transitions to the blocking state and then the forwarding state.
Answer: C
Explanation:
First, the port will transition to the blocking state, immediately upon the change, then it will transition to the new RSTP states of learning and forwarding.
Port States
There are only three port states left in RSTP that correspond to the three possible operational states. The 802.1D disabled, blocking, and listening states are merged into a unique 802.1w discarding state.
STP (802.1D) Port State
RSTP (802.1w) Port State
Is Port Included in Active Topology?
Is Port Learning MAC Addresses?
Disabled
Discarding
No
No
Blocking
Discarding
No
No
Listening
Discarding
Yes
No
Learning
Learning
Yes
Yes
Forwarding
Forwarding
Yes
Yes
Q15. Refer to the exhibit.
All switches have default bridge priorities, and originate BPDUs with MAC addresses as indicated. The numbers shown are STP link metrics.
After STP converges, you discover that traffic from switch SWG toward switch SWD takes a less optimal path. What can you do to optimize the STP tree in this switched network?
A. Change the priority of switch SWA to a lower value than the default value.
B. Change the priority of switch SWB to a higher value than the default value.
C. Change the priority of switch SWG to a higher value than the default value.
D. Change the priority of switch SWD to a lower value than the default value.
Answer: D
Explanation:
In this topology, we see that all port paths and priorities are the same, so the lowest MAC address will be used to determine the best STP path. From SWG, SWE will be chosen as the next switch in the path because it has a lower MAC address than SWF. From SWE, traffic will go to SWC because it has a lower MAC address, and then to SWD, instead of going from SWE directly to SWD. If we lower the priority of SWD (lower means better with STP) then traffic will be sent directly to SWD.