Announcement

Collapse
No announcement yet.

DNSLOOKUP and NETTIME

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts


  • DNSLOOKUP and NETTIME

    I can't get DNSLOOKUP to pull an IP address from pool.ntp.org, nor can I get a time via NETTIME even when using a static IP. I'm connected through a router, but I have validated NTP and DNS work from a computer connected to the same router. What am I missing?


  • #2
    In the NETTIME box when you click on "IP address lookup", can you put the url of a time server in there and have it find the correct IP? Thats what I did and it works fine. I believe I used "time.google.com" and my UDP port in my NETTIME instruction is set to 123.

    If your PLC is unable to find the IP for a url then my guess would be that it has no internet connection. Try using ping instruction to ping both the router on your network and also a big dns server like 8.8.8.8. or 4.2.2.3 or 9.9.9.9. If you cannot ping the router then you have a LAN issue, if you can ping the router but not a DNS server then you have a WAN issue.
    Last edited by MikeN; 11-12-2019, 03:05 PM.

    Comment



    • #3
      Double check the configured Gateway address of your Do-more PLC. Also, the DNS Server address. The Gateway definitely needs to be on the same subnet as your PLC. The DNS does not have to be (but will require a valid Gateway if not on the same subnet). This is under PLC->System Information menu.

      Click image for larger version

Name:	GeneralInfo1.png
Views:	154
Size:	38.7 KB
ID:	126542

      There are 10 kinds of people in this world, those who know binary, and those who do not.

      Comment



      • #4
        The Gateway points to the router. The DNS should be accessible ( same WAN as the router). I can connect through the router with my PC, but the BRX times out.

        Comment



        • #5
          What is your actual IP Address, Subnet Mask, and Gateway Address?
          There are 10 kinds of people in this world, those who know binary, and those who do not.

          Comment



          • #6
            Are you using a proxy server?

            Comment



            • #7
              Originally posted by franji1 View Post
              What is your actual IP Address, Subnet Mask, and Gateway Address?
              IP: 192.168.7.11
              Subnet: 255.255.255.0
              Gateway: 192.168.7.1

              Originally posted by pbw View Post
              Are you using a proxy server?
              No, not using a proxy

              Originally posted by MikeN View Post
              In the NETTIME box when you click on "IP address lookup", can you put the url of a time server in there and have it find the correct IP? Thats what I did and it works fine. I believe I used "time.google.com" and my UDP port in my NETTIME instruction is set to 123.

              If your PLC is unable to find the IP for a url then my guess would be that it has no internet connection. Try using ping instruction to ping both the router on your network and also a big dns server like 8.8.8.8. or 4.2.2.3 or 9.9.9.9. If you cannot ping the router then you have a LAN issue, if you can ping the router but not a DNS server then you have a WAN issue.
              Yes, I can use the IP lookup and the instruction finds an address for the PLC instruction. It just times out trying to connect. From a PC connected to the same router I can open web pages, and complete DNS and NTP requests.

              Comment



              • #8
                What is your DNS setting?

                Comment



                • #9
                  Originally posted by BobO View Post
                  What is your DNS setting?
                  DNS is set to 192.168.2.30, which is outside the router. Gateway is set to the router's address. This is the logic I am using. It times out on DNSLOOKUP.

                  Click image for larger version

Name:	Annotation 2019-11-19 134738.jpg
Views:	73
Size:	54.5 KB
ID:	126683

                  Comment



                  • #10
                    Try using the Google DNS (8.8.8.8) as the primary DNS server and see if that clears it up.
                    If you have an urgent issue, please contact AutomationDirect's Technical Support team.

                    AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

                    Comment



                    • #11
                      Originally posted by Do-more PE View Post
                      Try using the Google DNS (8.8.8.8) as the primary DNS server and see if that clears it up.
                      No difference. I have verified that DNS and SNTP both work from my PC behind the router, but the BRX times out.

                      Comment



                      • #12
                        Every time I have had issue like this it has been a gateway/router issue, or the PLC is not pointed to the correct gateway and DNS in the PLC's configuration.

                        Comment

                        Working...
                        X