A network engineer configured an Ethernet switch using these commands.
Switchone(config) # Spanning-tree portfast bpdufilter default
Which statement about the spanning-tree portfast feature on the switch is true?
A.
If an interface is enabled for portfast receives BDPU, the port goes through the spanning-tree
listening, learning, and forwarding states.
B.
If an interface is enabled for portfast receives BDPU, the port does not go through the
spanning-tree listening, learning, and forwarding states.
C.
If an interface is enabled for portfast receives BDPU, the port is shut down immediately.
D.
If an interface is enabled for portfast receives BDPU, the port goes into the spanning-tree
inconsistent state.
I’d disagree and say C here.
spanning-tree bpduguard enable (Puts port in errdisable upon receiving any bpdu). https://supportforums.cisco.com/document/45136/importance-bpdu-guard-and-bpdu-filter
Port is shutdown (err-disable) if it has bpduguard enabled and it receives a bpdu.
With bpdufilter as described here the bpdu is ignored and the port forwards immediately. Portfast causes it to bypass the normal spanning tree states.
So B is correct. That is not a desirable result though.
BPDUfilter is dangerous to the stability of your network. BPDU’s are there for a reason.
In his link, it says
Global mode
spanning-tree portfast bpdufilter default (It enables bpdufiltering on ports that have port-fast configuration, so it sends a few bpdu while enabling port then it filters bdpu unless receives a bpdu, after that it changes from port-fast mode and disables filtering for port to operate like a normal port because it has received bpdu).
It’s not bpduguard but bpdufilter which is configured here
STP PortFast causes a Layer 2 LAN interface configured as an access port to enter the forwarding state immediately, bypassing the listening and learning states. However, the “Spanning-tree portfast bpdufilter default” command specifies that if a BPDU is received on that port, then the default action of STPof listening, learning, and forwarding states should be used.
As per the literature I have read, the use of ‘default’ keyword in the command specifies that IF a BPDU is received on that port, then go through all three stages/states of the normal feature. So to sum it up, I think (just a thought) that network administrator gave this command as an insurance policy, that if someone attaches another switch or device which has potential to cause loops in the topology ON THIS SPECIFIC PORT/INTERFACE; then the whole STP theorem will be applied on it.
The BPDU filtering feature can be globally enabled on the switch or can be enabled per interface, but the feature operates with some differences.
At the global level, you can enable BPDU filtering on Port Fast-enabled interfaces by using the spanning-tree portfast bpdufilter default global configuration command. This command prevents interfaces that are in a Port Fast-operational state from sending or receiving BPDUs. The interfaces still send a few BPDUs at link-up before the switch begins to filter outbound BPDUs. You should globally enable BPDU filtering on a switch so that hosts connected to these interfaces do not receive BPDUs. If a BPDU is received on a Port Fast-enabled interface, the interface loses its Port Fast-operational status, and BPDU filtering is disabled.
http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560_scg/swstpopt.html
Took the 300-115 exam yesterday, passed with 955/1000 points!
Got 40 questions in total, a lot of new questions, LABs: LACP, AAAdot1x and HSRP.
I got all questions from passleader 300-115 exam dumps (got vce and pdf files from: https://tr.im/gMzjr), all new questions were same as my exam, still valid until now!
Here are some new questions that appeared in my exam:
Q1
When SDM templates are configured, which action must be performed for the configuration to take effect?
A. reload
B. shutdown
C. write memory
D. backup config
Q2
Which statement about the MAC address sticky entries in the switch when the copy run start command is entered is true?
A. A sticky MAC address is retained when the switch reboots.
B. A sticky MAC address can be a unicast or multicast address.
C. A sticky MAC address is lost when the switch reboots.
D. A sticky MAC address ages out of the MAC address table after 600 seconds.
Q3
Enablement of which feature puts the port into err-disabled state when the port has PortFast enabled and it receives BPDUs?
A. BPDU filtering
B. BackboneFast
C. EtherChannel
D. BPDU guard
Q4
Interfaces are assigned to a VLAN, and then the VLAN is deleted. Which state are these interfaces in after the VLAN is deleted?
A. They remain up, but they are reassigned to the default VLAN.
B. They go down until they are reassigned to a VLAN.
C. They go down, but they are reassigned to the default VLAN.
D. They remain up, but they are reassigned to the native VLAN.
Q5
Which feature is automatically configured when an administrator enables a voice VLAN?
A. 802.1Q trunking
B. PortFast
C. QoS
D. private VLANs
Q6
Which statement describes one major issue that VTP can cause in an enterprise network when a new switch is introduced in the network in VTP mode server?
A. It can cause network access ports to go into err-disabled state.
B. It can cause a network-wide VLAN configuration change if the revision number on the new switch is higher.
C. It can cause a network-wide VLAN configuration change if the revision number on the new switch is lower.
D. It can cause routing loops.
Good Luck To You!
[Update]
New 300-115 Exam Questions and Answers Updated Recently (7/Feb/2016):
NEW QUESTION 1
Refer to the exhibit, which statement abort the current configuration on port GigabitEthernet2/0/1 is true?
!
interface GigabitEthernet2/0/1
switchport access vlan 700
switchport trunk allowed vlan 200,300,700
switchport mode trunk
end
!
A. It is an access port configured for a phone and a PC
B. It is a trunk port and the native VLAN is VLAN1
C. It is a trunk port and the natrve VL AN m VLAN 700
D. It is an access port in VLAN 700
Answer: B
NEW QUESTION 2
Which two statements about default FHRP behavior are true? (Choose two.)
A. A backup GLBP active virtual gateway can become active only if the current active virtual gateway fails.
B. Preemption is enabled by default.
C. Unless specifically Configured, the priority of an HSRP router is 200.
D. A standby HSRP router becomes active if it has a higher priority than the priority of the current active router.
E. A VRRP backup virtual router becomes the master router if its priority is higher than the priority of the current master router.
Answer: DE
NEW QUESTION 3
If StormControl is enabled on a port and the traffic reachesthe configured level, which two actions can be configured to occur? (Choose two.)
A. Trap
B. notify admin
C. redirect traffic
D. log
E. shut down
Answer: AC
NEW QUESTION 4
Which two options are advantages of deploying VTPv3? (Choose two.)
A. It stores the VTP domain password securely as a SHA-1 hash.
B. It adds an FCS field at the end of each VTP frame for consistency checking.
C. It supports the propagation of private VLANs.
D. It supports the use of AES to encrypt VTP messaging.
E. It can be configured to allow only one VTP server to make changes to the VTP domain.
Answer: DE
NEW QUESTION 5
Which statement about HSRP, GLBP, and VRRP is true?
A. VRRP group members communicate using multicast address 224.0.0.102.
B. MAC address 0000.0c07.acOc indicates that default gateway redundancy is provided through GLBP.
C. HSRP group members communicate using multicast address 224.0.0.18.
D. GLBP uses UDP port 3222 (source and destination) for hello messages.
Answer: A
NEW QUESTION 6
……
P.S. These New 300-115 Exam Questions Were Just Updated From The Real 300-115 Exam, You Can Get The Newest 300-115 Dumps In PDF And VCE From — http://www.passleader.com/300-115.html (242q VCE and PDF)
Good Luck!
Besides, that new 242Q 300-115 Dumps are Available here for Free:
https://drive.google.com/open?id=0B-ob6L_QjGLpV1dGa2Q3czNVNG8
Best Regards!
New Question 3
A & E right
The actions are shutdown and trap
storm-control action shutdown
storm-control action trap
New Question 5
D is the right answer.
VRRP multicast is 224.0.0.18
VRRP mac address is 0000.5e00.01xx ( xx is vrrp group)
HSRP mac address is 0000.0c07,acxx (xx is standby group)
HSRP multicast is 224.0.0.2
HSRP UDP port 1985
GLBP mulitcast is 224.0.0.102
GLBP mac address is 0007.b4xx.xxyy( xxxx is six zero bit followed by 10 digit group , yy is the virtual forwarder)
GLBP port is 3222