def _isIp(value):
    """
    Check if the input string represents a valid IP address.

    A valid IP can be one of the two forms:

    1. A string that contains three '.' which separate the string into
    four segments, each segment is an integer.

    2. A string be either "INVALID_IP(XXXl)" or "AUTO/NONE(XXXl)",
    where XXX is a long value.

    Return a tuple, first element in the tuple is a boolean tells the validation result, while
    the second element contains the error message if there is one.
    """
    addrArray = value.split(".")
    if not len(addrArray) == 4:
        if value.startswith("INVALID_IP") or value.startswith("AUTO/NONE"):
            tail = value.split("(")
            if len(tail) == 2:
                longStrParts = tail[1].split("l")
                if len(longStrParts) == 2:
                    try:
                        int(longStrParts[0])
                        return True, None
                    except ValueError:
                        return False, "Invalid ip string: '{}'".format(value)
        return False, "Invalid ip string: '{}'".format(value)
    else:
        for segments in addrArray:
            try:
                segmentVal = int(segments)
            except ValueError:
                return (
                    False,
                    "Ip segment is not a number: '{}' in ip string: '{}'".format(
                        segments, value
                    ),
                )
            if not 0 <= segmentVal <= 255:
                return (
                    False,
                    "Ip segment is out of range 0-255: '{}' in ip string: '{}'".format(
                        segments, value
                    ),
                )
        return True, None