Acknowledgment

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

An acknowledgment is an 802.11 control message confirming receipt of a frame.

An acknowledgment, or Ack, is a control message confirming that a frame arrived successfully. In 802.11, the receiver sends an Ack after receiving a frame; if the sender does not receive it, the frame is retransmitted. section 19.1.3

Use the acknowledgment mechanism to understand wireless frame delivery:

• Classify Ack as an 802.11 control message, alongside request-to-send (RTS) and clear-to-send (CTS). section 19.1.3
• Send the Ack after successfully receiving a frame, allowing the sender to verify delivery across an unreliable wireless medium. section 19.1.3
• Retransmit the frame when the expected Ack is absent. section 19.1.3
• Distinguish an 802.11 Ack from DHCPACK, which confirms and finalizes an IP address lease, and from TFTP acknowledgments, which confirm ordered file blocks. section 4.1.1 section 8.1.1

Wireless frame delivery

A wireless device receives a data frame and returns an Ack. If that Ack is lost or never arrives, the sender retransmits the original frame. section 19.1.3

Figure 19.4 RTS, CTS, and Ack messages facilitate smooth communication over the medium. RTS asks for permission to transmit a frame, and CTS grants permission. Ack acknowledges receipt of the frame.

Visualizes Ack with RTS and CTS as control messages that facilitate frame delivery over the wireless medium. section 19.1.3

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes

Explains control-frame classification, receiver confirmation, and retransmission, but does not detail timing or frame fields.

Examples

Uses wireless frame delivery and contrasts DHCP lease confirmation with TFTP block acknowledgments.

What you can do after

Evaluate whether a wireless frame was confirmed and understand why the sender retransmits it.

How it connects

Connects 802.11 control frames with data frames, RTS/CTS, wireless reliability, DHCPACK, and TFTP acknowledgments.

liveBookmanning.com

Read Acing the CCNA Exam: Volume 2 Advanced Networking and Security on liveBook Get the book at manning.com

Also explained in

• 

  liveBookmanning.com
  Kafka for ArchitectsAn acknowledgment is a confirmation that a message or delivery operation has been received or completed.
• 

  liveBookmanning.com
  Apache Kafka in ActionAn acknowledgment (ack) is a Kafka broker response indicating the configured level of message receipt or persistence.
• 

  liveBookmanning.com
  Akka in Action, Second EditionAn acknowledgment is a message or signal confirming that a sent message or operation has been received or processed.

Compare how 4 books explain acknowledgment →

Related concepts

• TCPused by · TCP is a connection-oriented transport-layer protocol that provides reliable, ordered delivery of byte streams between network endpoints.
• primary nodeproduced by · A primary node is a designated authoritative or coordinating member of a distributed system, typically responsible for accepting operations or coordinating replicated state.
• network threadproduced by · A network thread is a broker thread that handles network communication and contributes to the broker's request-processing capacity.
• Kafka producerused by · A Kafka producer is an application or client that publishes records to Kafka topics.
• producerused by · A producer is an entity or process that creates or supplies values, data, messages, events, or work for another entity to consume.
• synchronous replicationused by · Synchronous replication is a replication method in which an operation is acknowledged or completed only after required replicas have confirmed the change.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.