Which command blocks the hosts 199.68.111.199, 202.177.9.1, and 211.55.67.11 using Standard Access List 25?

Which command blocks the hosts 199.68.111.199, 202.177.9.1, and 211.55.67.11 using Standard Access List 25?

• A. access-list 25 deny host 199.68.111.199; deny host 202.177.9.1; deny host 211.55.67.11
• B. access-list 25 permit any
• C. access-list 25 deny host 199.68.111.199
• D. access-list 25 deny host 202.177.9.1; deny host 211.55.67.11

Answer: (A)

Standard ACLs filter traffic by the source IP address. To block several specific hosts, put a deny statement for each host in the same ACL. Since you want to block three distinct IPs, you need three separate deny entries in the ACL, one for each address. When a packet from any of those addresses matches a deny statement, it is dropped. For all other sources, traffic can pass if you include a final permit statement (or rely on the implicit permit for non-matching traffic, depending on the IOS version and configuration). Among the options, denying each of the three IPs in one ACL blocks all three hosts, whereas denying only one or two hosts or permitting all traffic would not meet the requirement.

Standard ACLs filter traffic by the source IP address. To block several specific hosts, put a deny statement for each host in the same ACL. Since you want to block three distinct IPs, you need three separate deny entries in the ACL, one for each address. When a packet from any of those addresses matches a deny statement, it is dropped. For all other sources, traffic can pass if you include a final permit statement (or rely on the implicit permit for non-matching traffic, depending on the IOS version and configuration). Among the options, denying each of the three IPs in one ACL blocks all three hosts, whereas denying only one or two hosts or permitting all traffic would not meet the requirement.