单项选择题 Refer to the exhibit.Statements A,B,C,and D of ACL 10 have been entered in the shown order and appled to interface E0 inbound,to prevent all hosts(except those whose addresses are the first and last IP of subnet 172.21.1.128/28) from accessing the network.But as is,the ACL dose not restrict anyone from the network.How can the ACL statements be re-arranged so that the system works as intended?（）

单项选择题 Which statement is correct regarding the operation of DHCP?（）

单项选择题 Refer to the exhibit. An administrator pings the default gateway at 10.10.10.1 and sees the output as shown. At which OSI layer is the problem?（）