Hi Rich,

Thanks for the reply.

Some updates:

1. Our DNS server is "Infoblox appliance".

2. When we had a delay, we found that there was a "AAAA" query along with "A" query.

I did further debugging with "tcpdump" and able to narrow down on the difference in behavior between "debian" and "alpine" images.

In debian:

If ipv6 is disabled (net.ipv6.conf.default.disable_ipv6 = 1)

Then the "nslookup" (or name resolution) does not do a "AAAA" query

In alpine:

If ipv6 is disabled (net.ipv6.conf.default.disable_ipv6 = 1)

Then the "nslookup" (or name resolution) does an "AAAA" query along with "A" query

Is this intentional?

Also, I was wondering if there was any way to disable AAAA query in name resolution?

Kind Regards,

Srinivasa Raghavan.

On Thu, Sep 28, 2017 at 10:25 PM, Rich Felker <dalias@libc.org> wrote:

On Thu, Sep 28, 2017 at 12:28:55PM +0200, Szabolcs Nagy wrote:
> * Srinivasa Raghavan <raghav135@gmail.com> [2017-09-28 15:45:28 +0530]:
> > When using "Alpine" docker image which uses musl-libc, we are facing delay
> > when we do operations like below in our production environment,
> > 1. ping <name>
> > 2. nslookup <name>
> > 3. traceroute <name>
> > 4. http request from node.js
> >
>
> this bug may be related:
> https://github.com/rancher/rancher/issues/9961

Yes, I just filed it after reading the discussion on IRC and this bug
report that was linked as describing similar behavior:

https://github.com/rancher/rancher/issues/4177#issuecomment-332571951

This really requires a fix on the rancher-dns side. I'm not sure
exactly what glibc is doing, but it couldn't be giving the behavior
you want without doing something wrong: it's falling back and trying
different search domains when it hasn't been told that the first one
doesn't exist, only that the nameserver is experiencing a problem.

Rich