Question 1:

Which of the following is the correct wildcard mask for a subnet with a 255.255.248.0 subnet mask?

The correct answer is: 0.0.7.255

Explanation:
To determine the correct wildcard mask, we first need to understand the relationship between subnet masks and wildcard masks:

Subnet Mask: A subnet mask defines the network portion of an IP address. Here, we have a subnet mask of 255.255.248.0.
Wildcard Mask: A wildcard mask is the inverse of the subnet mask, often used in access control lists (ACLs) and certain routing protocols. To calculate the wildcard mask, you subtract each octet of the subnet mask from 255.

Step 1: Subtract Each Octet from 255
Subnet Mask: 255.255.248.0
First octet: 255 – 255 = 0
Second octet: 255 – 255 = 0
Third octet: 255 – 248 = 7
Fourth octet: 255 – 0 = 255

Step 2: Resulting Wildcard Mask
The result of these calculations gives us the wildcard mask: 0.0.7.255

This matches Option 4.

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