noseka1

How to disable AAAA lookups?

Problem description

The corporate DNS server that is outside of our control doesn't handle AAAA queries properly. When sent a AAAA query, the DNS server doesn't respond. A properly working DNS server returns NOERROR, ANSWER: 0, if there is no AAAA record for a given name. Misconfigured DNS server doesn't send any response.

In an IPv6-enabled environment, the client tries to resolve both A and AAAA addresses. If the DNS server doesn't send any reply, the client repeats the query and eventually times out. Only after the AAAA query times out, the client will use the A address. Waiting for the timeouts renders utilities like curl, kubectl, oc, ... and others unusable.

Identifying the AAAA lookup problem

xeoncross

When using the linux utility dd, there is no visual output of the progress, how long it is going to take, or anything else. Easy to solve with the use of pv:

    % sudo fdisk -l
    % pv /dev/sda | dd of=/dev/sdb bs=100M

that’ll display the amount of data transferred, the elapsed time, the throughput speed, a nice progress bar, and the ETA. For devices that do not have a fixed size, let’s say, /dev/zero, there’ll be only a throughput display.

- http://www.yournearestbar.com/2011/10/monitoring-dd-with-a-progress-bar/