Everyday Ten Ask Cisco CCIE RS

1. Question: If the switch is enabled with dhcp snooping and the trusted interface is configured.The address acquisition is slow or the address is not obtained.

Answer: Maybe the snooping entry of dhcp is full. If the snooping entry is full, the switch will discard the dhcp packet. When troubleshooting, you can first look at dhcp .Whether there are many snooping entries, if there are more, check the spec to confirm whether the entries are sufficient.

2. Question: What happens when the priority of the spanning tree is set to 0?

Answer: If the priority of the switch spanning tree is set to 0, the default is the smallest and the switch is directly of the root bridge of the tree.

3. Question: Can FW do routing mode to be an attack defense strategy?

Answer: FW routing mode can only be NAT, like other security domains, anti-attack strategy light configuration can only be done in copper drum mode transparent mode.

4. Question: Turn on the global Bondi but no determine the entry, is the data forwarded?

Answer: When the global binding of an ip+mac entry does not exist, open the address-bind install all data is released.

5. Question: How do I restore an interface to its default value?

Answer: default interface gi0/1

6. Question: LLDP protocol transparent transmission problem?

Answer: When the switch supporting lldp protocol does not support the delivery of lldp packets, the lldp protocol can not be delivered in time. Unless the intermediate device does not support the lldp protocol device, the lldp packet can be delivered normally.

7. Question: When a firewall newly creates an aggregation port, the VLAN passes?

Answer: Aggregation cuts all vlans by default. Once routing mode or transparent mode is done, all vlans are automatically released.

8. Question: In static link aggregation, one link is unplugged from one end, and the other interface is still up, causing data to not be switched to another link.

Answer: In the middle is a photoelectric converter, the optical port is converted into multiple electrical ports, resulting in the other side not down.

9. Problem: Create a new ssh session and enter sh Pop up when the log: The connection to the device failed, crt disconnected from the server?

Answer: The connection failed because the received data has an invalid data. The solution is to replace crt.

10. Question: Received inferior BPDU

Answer: When the device is connected to the BPDU of the secondary priority, you can check whether the interface has a CRC error frame. The reason for this is that the optical fiber and the network cable are single-passed so that the non-root bridge device can only send BPDU. Root bridge equipment will think that the root bridge has been asked Therefore, the BPDU will be sent to become the root bridge. However, if the root bridge still exists, the secondary priority BPDU will be received. In this case, the network cable and optical fiber need to be replaced.

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