Instructions for sniffing DNS from the terminal mode in Device Configuration Utility

  1. Launch Device Configuration Utility and connect to your data logger.

  2. Click the Terminal tab.

  3. Type capital letter W, and press Enter.

  4. Enter the number that corresponds to IP Trace (for the CR1000X, it’s 23), then press Enter.

  5. Enter the number that corresponds to DNS (e.g., 1000), then press Enter.

  6. You should now see the press ESC to exit, any other key to renew timeout message. To create an export of the results, click the Start Export button.

  7. On the Choose an export file window, select a location where you can find the file and give it a name (For example, “mysniff.txt”). Click Save.

  8. Capture the results for a few minutes while the data logger attempts the HTTP operation. The data logger must complete a DNS lookup as part of this process. Then, wait a few more minutes. For best results, let the HTTPPost() instruction complete or fail twice for redundancy. Once done, click the End Export button. If the HTTPPost()instruction only runs once per day at midnight, testing may be difficult without a way to trigger it manually.

    Interpreting DNS Sniff file results:

    In the resulting file, the following message indicates that the data logger is attempting a DNS lookup on the network::

    11:21:00.003 sending DNS request ID 65130 for name "google.com" to server 0

    A message like the one below indicates a successful DNS lookup of the target server:

    10:27:00.003 dns_lookup: "google.com": found = 142.250.176.14

    If you see a message like the following, the DNS lookup has failed:

    11:21:00.028 dns_recv: "afakeURL.com": error 3 in flags

    NOTE:

    Your results will likely include lots of TTL messages, like the following. This is normal.

    10:26:59.358 dns_check_entry: "google.com": ttl 60