Which condition is necessary for a data-link receiver to distinguish a retransmitted frame from a new frame in a stop-and-wait protocol?
One-bit sequence numbering, typically 0 and 1, distinguishes new frames from duplicate retransmissions.
What is the main purpose of an acknowledgment (ACK) in an ARQ protocol?
ACKs provide feedback about successful frame reception.
Which error-detection method treats the bit sequence as a polynomial over GF(2) and uses polynomial division?
CRC computes a remainder using modulo-2 polynomial division.
For a CRC generator polynomial of degree r, how many CRC bits are appended to the transmitted frame?
The CRC remainder has at most r bits, so r check bits are appended.
Which type of error is guaranteed to be detected by a parity bit when an even-parity scheme is used?
A single parity bit changes parity for every odd number of flipped bits.