Which of the following cannot be the length of the IPv4 packet header?

Which of the following statements about router-on-a-stick are correct? (Multiple Choice)

In the network shown in the figure below, switch A and router A are connected through two links, and the two links are aggregated in manual load sharing mode. The aggregated port number is 1, and the aggregated link performs data when forwarding, you need to carry VLAN TAG 100. Switch A uses Trunk link. Which of the following configurations should be used for Switch A?

Which of the following statements about Trunk port and Access port are correct?

Network equipment running the SNMP protocol can take the initiative to report alarm information so that the network administrator can discover the fault in time.