IP datagram has arrived with following partial information in the header (in…

Step 1: Find Header Length (IHL field)

First byte = 45

In IPv4:

• First 4 bits → Version

• Last 4 bits → IHL (Internet Header Length)

45 (Hex) = 0100 0101 (Binary)

So,

• Version = 0100 = 4 (IPv4)

• IHL = 0101 = 5

IHL is measured in 32-bit words.

Header Length =
IHL × 4 bytes = 5 × 4 = 20 bytes

Step 2: Find Total Datagram Size

Total Length field = 00 54 (Hex)

Convert to decimal:

0x54 = (5 × 16) + 4 = 84 bytes

So,

Total Datagram Size = 84 bytes

Step 3: Find Payload (Useful Data)

Payload = Total Length − Header Length

Payload = 84 − 20 = 64 bytes

Step 4: Calculate Efficiency

Efficiency=Useful DataTotal Datagram Size×100\text{Efficiency} = \frac{\text{Useful Data}}{\text{Total Datagram Size}} \times 100Efficiency=Total Datagram SizeUseful Data​×100 =6484×100= \frac{64}{84} \times 100=8464​×100 =0.7619×100= 0.7619 \times 100=0.7619×100 =76.19%= 76.19\%=76.19%

Final Answer:
Efficiency of the datagram ≈ 76.19% (≈ 76%)