Close - Close the Connection

The module is designed to close the connection without returning any response to the client.

In TCP mode, it immeditaly sends a TCP packet with the FIN (Finish) flag to the client, gracefully terminating the connection.

In UDP mode, no response is sent, resulting in a timeout.

Category: Empty responses

Format

close.yourdomain.com

This module has no parameters.

Examples

In UDP mode, the connection is terminated without sending any response, leading to a timeout. The client makes three attempts:

# dig close.yourdomain.com @127.0.0.1

;; communications error to 127.0.0.1#53: timed out
;; communications error to 127.0.0.1#53: timed out
;; communications error to 127.0.0.1#53: timed out

; <<>> DiG 9.18.10-2-Debian <<>> close.yourdomain.com @127.0.0.1
;; global options: +cmd
;; no servers could be reached

Download PCAP File

In TCP mode, the connection is gracefully terminated without sending any response. Once again, the client makes three attempts to resolve the error:

# dig close.yourdomain.com @127.0.0.1 +tcp

;; communications error to 127.0.0.1#53: end of file
;; communications error to 127.0.0.1#53: end of file
;; communications error to 127.0.0.1#53: end of file

; <<>> DiG 9.18.10-2-Debian <<>> close.yourdomain.com @127.0.0.1 +tcp
;; global options: +cmd
;; no servers could be reached

Download PCAP File

Like other features, you can append anything to the feature name to avoid receiving cached responses from the target DNS resolver. This forces the target resolver to actively communicate with our PolarDNS server instead of responding with cached answers. Using a random number is the most effective strategy:

# dig close${RANDOM}.yourdomain.com @10.211.55.2

;; communications error to 10.211.55.2#53: timed out
;; communications error to 10.211.55.2#53: timed out
;; communications error to 10.211.55.2#53: timed out

; <<>> DiG 9.18.10-2-Debian <<>> close4958.yourdomain.com @10.211.55.2
;; global options: +cmd
;; no servers could be reached

Download PCAP File

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