RC7611 DNS 5 second delay

IoT Modules RC76
1

We are running a linux computer with the RC7611 LTE module for network connectivity. We have noticed that DNS is taking 5 seconds resolve. After running a tcpdump, we can see that the DNS is sending an A (ip4) and AAAA (ip6) DNS request simultaneously. For some reason, the LTE modem can’t process the 2 requests at the same time, so we receive the ip4 DNS response, but not the ip6 response. This makes the DNS lookup timeout after 5 seconds, and then it retries. When linux retries the lookup, it uses “single-request” to sequentially send the ip4 and ip6 request (instead of parallel). This succeeds in 350ms. We can set the “single-request” dns option to get around this issue.

Has anyone else experienced this DNS issue?

2

Hi @chris.miller,

Welcome to our community!

Based on what you describe, I see you are using 2 interfaces at the same time.
If you have no specific reason for using 2 interfaces at the same time, then you should only use 1 interface with IPV4 or IPv6 for your use case.
You can use the AT command to define a single interface.

Example is below:

AT+CGDCONT=1,“IP”,“APNname” ← for IPv4 interface

AT+CGDCONT=1,“IP”,“IPV6” ← for IPv6 interface

Thanks,