Consider the following 32 bit binary value representing an IPv4 address in dotted binary notation 11001100.00110011.10101010.01010101. What is the equivalent dotted decimal IP address for this binary value?

Introduction / Context:
This question assesses your ability to convert an IPv4 address written in dotted binary notation into the more familiar dotted decimal format. Being comfortable with binary to decimal conversion for octets is important for subnetting, interpreting network masks, and troubleshooting IP addressing problems in real world networks.

Given Data / Assumptions:
- The IPv4 address is given as four groups of eight bits separated by dots: 11001100.00110011.10101010.01010101.
- Each group of eight bits represents one octet of the IPv4 address.
- We need to convert each binary octet into its decimal value using base 2 positional weights.
- No special subnetting or mask information is required beyond the conversion itself.

Concept / Approach:
An IPv4 address consists of four octets, each ranging from 0 to 255 in decimal. Each octet is an 8 bit binary number with bit weights 128, 64, 32, 16, 8, 4, 2, and 1 from left to right. To convert from binary to decimal, you add the weights corresponding to bit positions that are set to 1. You perform this operation separately for each octet and then join the resulting decimal values with dots to form the dotted decimal notation.

Step-by-Step Solution:
Step 1: Take the first octet 11001100. The bits set to 1 are at positions 128, 64, 8, and 4. Add them to get 128 + 64 + 8 + 4 which equals 204.Step 2: Take the second octet 00110011. The bits set to 1 are at positions 32, 16, 2, and 1. Add them to get 32 + 16 + 2 + 1 which equals 51.Step 3: Take the third octet 10101010. The bits set to 1 are at positions 128, 32, 8, and 2. Add them to get 128 + 32 + 8 + 2 which equals 170.Step 4: Take the fourth octet 01010101. The bits set to 1 are at positions 64, 16, 4, and 1. Add them to get 64 + 16 + 4 + 1 which equals 85.Step 5: Combine the four decimal octets to form the dotted decimal address 204.51.170.85.

Verification / Alternative check:
You can verify the conversion by reversing the process for one of the octets. For example, take decimal 204. Subtract 128 to get 76, subtract 64 to get 12, subtract 8 to get 4, subtract 4 to get 0. The remaining zero confirms that 204 is represented by bits 128, 64, 8, and 4 all set to 1, which corresponds to the binary pattern 11001100. Performing similar checks for the other octets confirms the correctness of the calculation.

Why Other Options Are Wrong:
192.51.160.85 is incorrect because the first octet would require a different binary pattern, and 160 instead of 170 in the third octet shows a miscalculation. The values 204.19.170.85 and 204.51.168.95 contain incorrect decimal conversions of one or more octets, indicating wrong combinations of bit weights. The option 204.83.170.85 misrepresents the second octet and does not match the binary representation given.

Common Pitfalls:
Candidates often make mistakes by misplacing bit weights, especially confusing 32 and 64 or 8 and 16. Another error is to try to convert all 32 bits at once instead of treating each octet independently. Practicing with a simple table of powers of two and marking which bits are set helps reduce these errors and speeds up exam calculations.

Final Answer:
The binary IP address 11001100.00110011.10101010.01010101 corresponds to the dotted decimal address 204.51.170.85.