Hi,

I am using lwip as part of the espressif/arduino-esp32 library and there is
something I don't understand.

My question is about DNS implementation of lwip:
https://github.com/espressif/arduino-esp32/blob/master/tools/sdk/include/lwip/lwip/dns.h

If I understand correctly there is a lookup table, which contains the host
names, which have been queried before and their ip adress. Can I add a host
to that lookup table during runtime?

So what I want is this: The ESP32 wakes up and only does the DNS query (
dns_gethostbyname), if the IP address of an MQTT server has changed,
because an IP change of that server is not likely to happen often. So I
would save the IP address over deep sleep and use it again, when the ESP
wakes up. Do I need a dynamic host list for that (the DNS_LOCAL_HOSTLIST
macro is undefined now)? Or can I edit the lookup table directly?

Best,

Roman
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