On which options are standard access lists based?
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A. B. C. D.D
Standard Access Lists are used to filter packets based on the source IP address of the packet. They are called "standard" because they only examine the source address field of the IP header. They are numbered from 1 to 99 and 1300 to 1999.
The correct answer is option D, "source address and wildcard mask". Standard Access Lists are based on the source address and a wildcard mask that identifies the bits that should be matched. A wildcard mask is a 32-bit number that is used to mask out the bits in the IP address that should be ignored when matching packets. The bits that are set to 0 in the wildcard mask are the bits that should be matched.
For example, if you wanted to create an access list that would only allow traffic from the host with IP address 192.168.1.10, you would use the following command:
access-list 10 permit 192.168.1.10 0.0.0.0
In this example, the access list is numbered 10 and it permits traffic from the host with IP address 192.168.1.10. The wildcard mask 0.0.0.0 indicates that all bits of the source IP address should be matched exactly.
If you wanted to create an access list that would block traffic from the entire 192.168.1.0/24 subnet, you would use the following command:
access-list 10 deny 192.168.1.0 0.0.0.255
In this example, the access list is numbered 10 and it denies traffic from the entire 192.168.1.0/24 subnet. The wildcard mask 0.0.0.255 indicates that only the last octet of the source IP address should be matched.
It's worth noting that standard access lists are generally less flexible than extended access lists, which can filter packets based on a wider range of criteria, including source and destination IP addresses, protocols, and ports.