Câu 62: 400-351: CCIE Wireless Written Exam

A router has two interfaces: Ethernet 0 is connected to the LAN and Ethernet 1 is connected to the Internet. The LAN is 20.20.20.0/24. All hosts on the LAN must be able to form TCP connections to any host on the Internet. Hosts on the Internet may not form TCP connections to hosts on the LAN, except to port 25 of a mail server on the LAN. The web server IP address is 20.20.20.100. Which configuration fulfills all the requirements?

1. A. interface ethernet 1 ip access-group 123 in ! access-list 123 permit tcp any 20.20.20.0 0.0.0.255 access-list 123 permit tcp any host 20.20.20.100 eq 25
2. B. interface ethernet 1 ip access-group 123 in ! access-list 123 permit tcp any 20.20.20.0 0.0.0.255 established access-list 123 permit tcp any host 20.20.20.100 eq 25 — đáp án hiện tại
3. C. interface ethernet 1 ip access-group 123 in ! access-list 123 permit tcp any host 20.20.20.100 eq 25 access-list 123 deny tcp any 20.20.20.0 0.0.0.255
4. D. interface ethernet 1 ip access-group 123 in ! access-list 123 deny tcp any 20.20.20.0 0.0.0.255 access-list 123 permit tcp any host 20.20.20.100 eq 25
5. E. interface ethernet 1 ip access-group 123 in ! access-list 123 permit tcp any host 20.20.20.100 eq 25 access-list 123 permit tcp 20.20.20.0 0.0.0.255 any