Chapter 1 – Implement VLAN based solution, given a network design and a set of requirements
QUESTION NO: 51
ISL is being configured on a Company switch. Which of the following choices are true regarding the ISL protocol? (Select two)
A. It can be used between Cisco and non-Cisco switch devices.
B. It calculates a new CRC field on top of the existing CRC field.
C. It adds 4 bytes of protocol-specific information to the original Ethernet frame.
D. It adds 30 bytes of protocol-specific information to the original Ethernet frame.
ISL adds a total of 30bytes to the Ethernet frame. A 26 byte header (10bytes identifies the VLAN ID) and a 4 byte trailer (containing a separate CRC).
QUESTION NO: 52
You are the network administrator tasked with designing a switching solution for the Company network. Which of the following statements describing trunk links are INCORRECT? (Select all that apply)
A. The trunk link belongs to a specific VLAN.
B. Multiple trunk links are used to connect multiple end user devices.
C. A trunk link only supports native VLAN.
D. Trunk links use 802.10 to identify a VLAN.
E. The native VLAN of the trunk link is the VLAN that the trunk uses for untagged packets.
A trunk is a point-to-point link that transmits and receives traffic between switches or between switches and routers. Trunks carry the traffic of multiple VLANs and can extend VLANs across an entire network. 100BaseT and Gigabit Ethernet trunks use Cisco ISL (the default protocol) or industry-standard IEEE 802.1Q to carry traffic for multiple VLANs over a single link. Frames received from users in the administratively-defined VLANs are identified or tagged for transmission to other devices. Based on rules you define, a unique identifier (the tag) is inserted in each frame header before it is forwarded. The tag is examined and understood by each device before any broadcasts or transmission to other switches, routers, or end stations. When the frame reaches the last switch or router, the tag is removed before the frame is transmitted to the target end station.
QUESTION NO: 53
Switch R1 has been configured with the root guard feature. What statement is true if the spanning tree enhancement Root Guard is enabled?
A. If BPDUs are not received on a non-designated port, the port is moved into the STP loop-inconsistent blocked state
B. IF BPDUs are received on a PortFast enabled port, the port is disabled.
C. If superior BPDUs are received on a designated port, the interface is placed into the root-inconsistent blocked state.
D. If inferior BPDUs are received on a root port, all blocked ports become alternate paths to the root bride.
Answer: C Explanation:
Root guard is configured on a per-port basis, and does not allow the port to become a STP root port. This means that the port is always STP-designated. If there is a better BPDU received on this port, root guard will put the port into root-inconsistent STP state, rather than taking the BPDU into account and electing a new STP root. Root guard needs to be enabled on all ports where the root bridge should not appear. In a way one can configure a perimeter around part of network where STP root is allowed to be located.
QUESTION NO: 54
What does the global command udld enable accomplish?
A. Enables all fiber-optic LAN ports for Unidirectional LINK Detection (UDLD)
B. Enables all copper media LAN ports Unidirectional Link Detection (UDLD)
C. Overrides the default UDLS setting for all ports
D. Globally enables all ports on the device for Unidirectional Link Detection (UDLS)
E. None of the other alternatives apply
QUESTION NO: 55
Which three statements about the Multiple Spanning Tree (MST) protocol (IEEE 802.1s) are true? (Choose three.)
A. To verify the MST configuration, the show pending command can be used in MST configuration mode.
B. When RSTP and MSTP are configured; UplinkFast and BackboneFast must also be enabled.
C. All switches in the same MST region must have the same VLAN-to-instance mapping, but different configuration revision numbers.
D. All switches in an MST region, except distribution layer switches, should have their priority lowered from the default value 32768.
E. An MST region is a group of MST switches that appear as a single virtual bridge to adjacent CST and MST regions.
F. Enabling MST with the “spanning-tree mode mst” global configuration command also enables RSTP.
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