Query DNS ipv6

Question

Server oracle linux 6.6
Oracle Enterprise 12c
With a sniffer I see that there are several requests DNS AAAA (ipv6) to my DNS Server local.
The query is : STANDARD QUERY 0X1212 AAAA "HOSTNAME"
The reply is : STANDARD QUERY RESPONSE 0X1212 SERVER FAILURE
In another server with similar features:
The query is : STANDARD QUERY 0X1456 AAAA "HOSTNAME"
The reply is : STANDARD QUERY RESPONSE 0X1456 NO SUCH NAME
From what I understand IPv6 queries always anticipate queries IPv4.
There is a way to change this order?
the idea is to avoid this unnecessary traffic even if it is minimal.
Thanks.

Answer 1

What you see is very common and also described in https://www.ietf.org/rfc/rfc4074.txt
It most likely means that your DNS server is not configured to provide IPv6 AAAA records, or perhaps your systems have different /etc/hosts files, which you might want to compare. It might be interesting to find out what causes the IPv6 DNS queries, but you can probably ignore it in case it is only a cosmetic issue.
> From what I understand IPv6 queries always anticipate queries IPv4.
I don't know what you mean by that, but if you do not need IPv6, I suggest to try disabling IPv6 in the kernel by adding an appropriate kernel paramter line at system startup, or by modifying /boot/grub/grub.conf and adding the following:
ipv6.disable=1
You can eventually also do the following:
echo"install ipv6 /bin/true"> /etc/modprobe.d/ipv6_disabled.conf