Keysight E36731A Manuel D'instructions page 54

More about IP addresses and dot notation
Dot-notation addresses ("nnn.nnn.nnn.nnn" where "nnn" is a byte value from 0 to 255) must be expressed with care,
as most PC web software interprets byte values with leading zeros as octal (base 8) numbers. For example,
"192.168.020.011" is equivalent to decimal "192.168.16.9" because ".020" is 16 expressed in octal, and ".011" (octal)
is "9" (base 10). To avoid confusion, use only decimal values from 0 to 255, with no leading zeros.
54 Keysight E36731A User's Guide