Your message dated Mon, 18 May 2020 20:22:48 +0200
with message-id <>
and subject line Re: Bug#960739: libc-bin: getaddrinfo() fails with EAI_AGAIN 
when the DNS query returns a large number of A and AAAA records.
has caused the Debian Bug report #960739,
regarding libc-bin: getaddrinfo() fails with EAI_AGAIN when the DNS query 
returns a large number of A and AAAA records.
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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--- Begin Message ---
Package: libc-bin
Version: 2.30-7
Severity: important
Tags: ipv6

Dear Maintainer,

When attempting to follow the instructions for installing the latest version of 
Docker Engine at I noticed that 'apt-get update' 
and curl were both
failing to resolve  The error message from both ping and 
curl was 
"Temporary failure in name resolution"

However, running 'host' yielded the following results: is an alias for has address has address has address has address has IPv6 address 
2600:9000:2202:c00:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:5000:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:7a00:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:9200:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:9600:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:9c00:3:db06:4200:93a1 has IPv6 address 
2600:9000:2202:a200:3:db06:4200:93a1 has IPv6 address 

After examining the source code for iputils-ping, I was able to determine that 
the cause of the
error message was getaddrinfo() returning EAI_AGAIN

The following workarounds were effective:

* curl -4 (Forcing curl to use IPv4 only)
* ping -4 (Forcing IPv4 ping to use IPv4 only)
* Forcing apt to use IPv4 by adding 'Acquire::ForceIPv4 "true";' to apt.conf

It is also noteworthy that not all hostnames with both A and AAAA records 
trigger this bug. In fact,
hostnames with a low total record count like have no problem 

root@sandbox:~# host has address has IPv6 address 2607:f8b0:4005:809::2004
root@sandbox:~# ping
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=63 
time=29.6 ms
--- ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2005ms
rtt min/avg/max/mdev = 29.572/37.733/42.045/5.774 ms

Please note that this bug also affects libc-bin 2.28-10 in buster.

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-9-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), 
LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages libc-bin depends on:
ii  libc6  2.30-7

Versions of packages libc-bin recommends:
ii  manpages  5.06-1

libc-bin suggests no packages.

-- Configuration Files:
/etc/gai.conf changed [not included]

-- no debconf information

--- End Message ---
--- Begin Message ---
* Mike Przybylski:

> Since you’ve pointed out pretty clearly from the pcap that Google
> and VirtualBox are having some bizarre interaction, I think we can
> close this as “not a bug.”  I apologize for taking up your time with
> it.

It's the DNS implementation in Virtualbox that's broken, particularly
in the area of TCP support.  Upstream glibc occasionally receives bug
reports about it, too.

--- End Message ---

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