Instructions:

• Answer 50 questions in 15 minutes.
• If you are not ready to take this test, you can study here.
• Match each statement with the correct term.
• Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. By default - what submode does PAgP operate in with the desirable and auto modes?
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
2 seconds (def)
Silent
Each physical interface has a different IP address. All physical interfaces point to a virtual interface called the standby address or VIP


2. What is the STP forwarding state?
By encapsulating each frame in a header and trailer
Half-duplex
If a unidirectional link is detected - the port continues normally - but the port is marked as undetermined and a syslog is generated
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs


3. Each switch port is a _____ ______
900 MHz - 2.4Ghz - and 5-6GHz
Collision domain
134 bits
All ports where root isn't expected


4. What is a proxy arp?

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5. One vlan should =
0-255
1 IP subnet
1- enable qos - 2-define qos parameters to be trusted - 3-make trust conditional - 4-instruct IP phone how to extnd boundary
Auto mode


6. RSTP learning state
Routers are assigned to common GLBP group. All routers can be active and can load balance
As a VLAN access map
Differentiated services code point
Incoming frames dropped - but MACs learned


7. How does packet forwarding work
Gateway load balancing protocol - cisco proprietary
Auto mode
Arp for local subnet - if on different subnet - will arp for dgw
900 MHz - 2.4Ghz - and 5-6GHz


8. What is step 1 of enabling IP source guard?
Configure and enable DHCP snooping
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
A VLAN that spans the entire fabric
Checks the source MAC in the header against the sender MAC in the ARP reply


9. What does port-security restrict do?
10-15%
Port stays up - but packets from violating MACs are dropped. Switch logs violating packets
2-8 FE - GE - or 10GE are bundled.
Etherchannel ports have inconsistent config


10. How many designated ports are there?
1 per segment
The standby becomes active and stays active by default. Preemption can be configured
Normal and aggressive
Switch(config-if)# glbp xx where xx = group number


11. What are the gotchas for uplinkfast?

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12. What is topology-basec caching?
The topology is pre-populated by downloading the topology DB into the FIB and dynamically updated. Called Cisco Express Forwarding
Causes switch to actively determine whether alternative paths exist to root bridge in case ther eis an indirect failure
Access
Very high L3 throughput - no access lists or port filtering - redundancy and resilience - advanced QoS


13. What are the 3 RSTP port types?
Data and voice over native vlan no QOS and no 802.1p trunk
Edge - root - and point to point
Cisco ILP and 802.3af
7 switches from root bridge


14. Does GLBP allow preemption?
Virtual Router Redundancy Protocol - pretty much the same as HSRP
Matching SSID - compatible data rate - authentication credentials
2
Yes


15. If one end of an Etherchannel (either type) is set to on and the channel doesn't form - what should you check?

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16. What types of links can be trunked?
FE - GE - and aggregated FE/GE Etherchannels
Arp for local subnet - if on different subnet - will arp for dgw
Immediate (class 2)
0-255


17. Where shoul dmultilayer switches be implemented?
If a unidirectional link is detected - the switch doesn't try to reestablish the link. ULD msgs are sent once/sec for 8 seconds - then the port is err-disabled
Frames that barely exceed 1518B or 1622B due to headers
Distribution layer
1-(opt) configure load balancing - 2-select the interface(s) - 3-assign the protocol - 4-select the mode and submode


18. 802.11a
Checks the destination MAC in the header against the target MAC in the ARP reply
0-255
Yes to both
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz


19. How does GLBP work?
Routers are assigned to common GLBP group. All routers can be active and can load balance
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
5 (0-4 with 4 being the highest)
0-255


20. How does a DHCP server send WLC addresses?
Option 43
Trusted ports
0-65535 (def 32768) lower=better
Two distribution switches that aggregate one or more access switches


21. How does the standby handle ARP issues after it becomes active?
By sending a gratuitous ARP
FE and GE
Port
Src-dst-ip


22. What is DSCP?
Frames that barely exceed 1518B or 1622B due to headers
The switch adds its MAC to the option 82 field so that the DHCP reply echoes back the switch's own information
Differentiated services code point
Root


23. What is the default FE duplex?
Normal and aggressive
Immediate (class 2)
Full duplex
Disabled - blocking - listening - learning - forwarding


24. What does IP source guard do?
1-(opt) set system priority - 2-select interface(s) - 3-assign the protocol - 4-set the mode - 5-(opt) set the port priority
Makes use of the DHCP snooping database and static ip source binding entries. If enabled - switch will test addresses
After another forwarding delay - the port can send and receive data frames - collect MAC addresses - and send and receove BDPUs
That they aren't using the same frequencies.


25. RSTP backup port
Port with redundant - but less deisrable connection to a segment. Possibly root candidate
Create 2 hsrp groups - each with the active router being different switches - then have clients point to each
Every hello interval regardless of whether BDPUs are received from root - allowing any switch to take an active role maintaining the topology
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac


26. Where should you change the network diameter value?
The number of STP instances needed ot support the desired topologies and whether to map a set of VLANs to each instance
Cisco recommends only on the root bridge
1 -2 -5.5 and 11 Mbps - Channels 1/6/11 - 2.4Ghz
Packets are discarded due to an ACL or policy action


27. Can two switches in the auto(PAgP) or passive (LACP) mode create a channel? Why?
No because they only participate if asked
Normal and aggressive
Should be used on access switches - can't be used on root - keeps enabled switch from becoming root by raising priority of switch and all ports - making them undesirable
Trusted or untrusted


28. How is RSTP synchronization accomplished?
All non-edge ports are discarding. After the root bridge is identified - the port with superior BDPU becomes root
To a VLAN and not to a VLAN interface (SVI)
Time between BDPUs sent by root bridge. Default of 2 seconds
Packets must be sent to the L3 engine for further processing


29. What is the GLBP AVG?
Admin down
One router is the active virtual gateway - has highest priority or IP in group - answers all ARP requests and gives MAC based on load balancing
19
Normal and aggressive


30. How do you configure DAI for statically configured IP addresses?
Real-time Transport Protocol
By an ARP access list that defines the permitted bindings
Embeds the tag within the frame
1-1005 (1 and 1002-1005 are reserved)


31. What is a BSS?
Real-time functions such as beacons and probes - encryption and interactions with the client at L2
Using a single WAP to centralize access and control over a group of wireless devices.
A private VLAN can be logically associated with a special secondary vlan
No


32. What is the range of PAgP channel group numbers?
On the left as you face the connector
1 to 64
RPR - RPR+ - and SSO
300 sec


33. What is the size of a TCAM value?
5 classes with 3 drop precedences
Single instance of STP for all VLANs. BDPUs are sent over trunks using the native VLAN with untagged frames. Dot1q based
They shorten their bridge table aging times from default (300sec) to the fowarding delay (15 sec)
134 bits - consisting of source and destination addresses and protocol information from the packet or frame


34. What is the default MTU?
The ASIC
Root - designated - blocking - alternate - forwarding (host)
Isl - dot1q - negotiate (default)
1500B


35. How does loop guard block ports?
All fiber-optic links between switches (must be enabled on both ends)
Incoming frames dropped - but MACs learned
Only for the offending VLAN on the port
Every switch and router in a network must be configured with appropriate QoS features and policies


36. How does the CEF L3 engine operate?

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37. How do you enable CEF?
It is enabled by default on all CEF capable switches
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information
7 switches from root bridge
Globally


38. What does a LAP do if it loses communication with it's WLC?
Compatible with 802.11b - up to 54Mbps in 12 data rates - 3 channels - 2.4Ghz
Src-dst-ip
For hosts that doesn't understand routing - the DGW is configured to reply with its own mac
Reboots and searches for a new WLC


39. What is the 80/20 rule?
The port will operate under 802.1D rules. If they are received on the same port - it will run 802.1D until the migration delay expires
RPR - RPR+ - and SSO
80% of the user traffic should stay in the VLAN
It updates the L2 headers with the proper src and dst MAC - L3 TTL - L3 checksum - and L2 checksum information


40. On what scope is DAI enabled?
Trunk
Per VLAN
A packet can't be switched in hardware with the FIB and must go to the L3 engine
4


41. How does HSRP port tracking work?

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42. Where is UDLD enabled?
Used when ACLs specify port ranges...used by TCAM
All fiber-optic links between switches (must be enabled on both ends)
Usually QoS from VOIP but not PC dataa
Protects STP when a physical malfunction only allows traffic in 1 direction - even though the link shows as up (cisco proprietary)


43. What are the 3 unlicensed frequencies?
2 strand MMF with MT-RJ or SC connectors
900 MHz - 2.4Ghz - and 5-6GHz
Time between BDPUs sent by root bridge. Default of 2 seconds
Up to 54Mbps - not cross-compatible - 12 to 23 clean channels - 5.8 Ghz


44. Does a WLC and a LAP need to be on the same subnet?
A host port goes up or down
No
A path is pre-arranged for priority along the complete path from source to destination using the RSVP protocol.
Switching Database Manager - configures and prunes TCAM partitions


45. Where is the QoS trust boundary usually configured on an IP phone?
Collision domain
134 bits - consisting of source and destination addresses and protocol information from the packet or frame
Usually QoS from VOIP but not PC dataa
All user ports that have portfast enabled


46. When looking at the sh spanning tree output - What does P2P denote?
A point to point port type
Controls where candidate root bridges can be connected and found on a network
Use sh interface on the interface and look for error counts > 10
FE - GE - and aggregated FE/GE Etherchannels


47. How does a Cisco IP phone connect upstream?
MAC addresses are learned from the source MAC of incoming frames. If the destination address is unknown - the frame is flooded out all except the receiving port.
0000.0c07.acxx where xx is the group number as a 2-digit hex value
Via an 802.1Q trunk or a single VLAN access port
The number of times the CEF table has bee flushed and regenerated as a whole


48. What are the 6 steps to configure 802.1x for port security?
1-enable AAA on switch - 2-define RADIUS servers - 3-define authentication method - 4-enable 802.1x on switch - 5-conf. 802.1x ports - 6-allow hosts
Listens to the first packet going to router and away from the router. If it can switch in both directions - it learns a shortcut path so subsequent packets can be switched without the RP
The frame tag contains a 3 but portion tagged from 0 (low) to 7 (high)
The distribution layer should have only L3 links


49. Of what significance are private VLANs
Local only
Trunk
By using an Ether-IP tunnel
Round robin - weighted - or host-dependent


50. What is a bridge ID made up of?
Root
Bridge priority and MAC
Hosts within a secondary can communicate with each other and with the primary - but not with another secondary vlan
80% of the user traffic should stay in the VLAN