Saturday, May 20, 2023

Now I know why zoom feature is available in operating system for.

I use to think why would an O/S feature is created as it sudden zoom ridiculous 10-100x of the current resolution. 

But as one age, it FINALLY make sense, all comes around! Let's give an example. Given the current view at current resolution of the following picture

Given the following webshot, what's the difference can you identify?

Sure, some with very good eye can spot but it would also take sometime to identify. But if you can zoom in, wouldn't that be nice?! In linux , try super + alt + 8, yes the 8 is not on the numpad. Now it should be clearly shown what is the difference.

The display might be too small, try open the image in a new window tab. It should be clearly seen that the vertical line is dashed whilst the horizontal line is dotted. Well that's the difference!

It is like the zoom feature allow one to inspect the DNA.. well, computer DNA.. :) 

Tuesday, March 7, 2023

how to setup mariadb galera cluster in docker container

 1. create network (one time)

   docker network create --subnet= mynet123

2. create image that can start service in container (one time)

   mkdir systemd

   cd systemd

   vim Dockerfile

   FROM almalinux

   ENV container docker

   RUN (cd /lib/systemd/system/; for i in ; do [ $i == systemd-tmpfiles-setup.service ] || rm -f $i; done);

   RUN rm -rf /lib/systemd/system/ \

   && rm -rf /etc/systemd/system/.wants/ \

   && rm -rf /lib/systemd/system/ \

   && rm -f /lib/systemd/system/ \

   && rm -f /lib/systemd/system/ \

   && rm -rf /lib/systemd/system/ \

   && rm -f /lib/systemd/system/*

   VOLUME [ “/sys/fs/cgroup” ]

   CMD ["/usr/sbin/init"]

3. build image (one time)

   docker build -t almalinux-md .

4. start the container in the background

   docker run -v /tmp/node1/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip --name node1  almalinux-md 

   docker run -v /tmp/node2/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip --name node2  almalinux-md

   docker run -v /tmp/node3/:/var/lib/mysql --detach --rm -it --privileged --net mynet123 --ip --name node3  almalinux-md  

5. attach it and so can install mariadb and gelera, etc

   docker exec -it node1 bash

   docker exec -it node2 bash

   docker exec -it node3 bash

6. install in all 3 nodes

   dnf install -y mariadb-server.x86_64  mariadb.x86_64 rsync python3-policycoreutils vim nc telnet epel-release.noarch mariadb-server-galera.x86_64

7. on first node

   systemctl start mariadb

   systemctl status mariadb

   [root@6c3d7f5bc394 /]# mysql -uroot

   MariaDB [(none)]> set password = password("password");


   systemctl stop mariadb


8. from step 5. wsrep_node_address and wsrep_node_name update to its corresponding name   

   [root@cfeee129fe92 /]# cat /etc/my.cnf.d/galera.cnf






   # Galera Provider Configuration



   # Galera Cluster Configuration



   # Galera Synchronization Configuration


   # Galera Node Configuration



   [root@cfeee129fe92 /]# 

9.  on first node, start the cluster



10. check on the first node,

    mysql -u root -ppassword -e "SHOW STATUS LIKE 'wsrep_cluster_size'"   


11. bring up the remaining nodes one by one

    systemctl start mariadb

    mysql -u root -ppassword -e "SHOW STATUS LIKE 'wsrep_cluster_size'"   

12. ready to write/read

mysql -u root -ppassword -e 'CREATE DATABASE playground;


INSERT INTO (type, quant, color) VALUES ("slide", 2, "blue");'

mysql -u root -ppassword -e 'SELECT * FROM;'

Thursday, February 24, 2022

Best place I think docker container is for

 docker container has been with us for many years. For software engineer which deal with legacy application, it can be intimidating to migrate to docker application. Because system stability, production investigation and quick fix and service stability surpasses every technology stack. At least that is for me, this cannot be compromise. 

So where is docker container is best for? Where do we start docker container for? For many people, if you google, they build the application into docker image and deploy. Sure, that can be done but for me, as a start, I think for learning purposes and best use cases. Here, I would like share my experience and best use cases.

code compiling

Many of us do code compiling and this is especially true if you want to deploy a bunch of application, modify here and there, build the binary , get the final result and then move on. Installing software packages into container will not taint the host. Modify the configuration also need not worry about taint the host. What is even more merrier, you don't have to clean up after you done compiling. One can just delete the container and start over. Guaranteed reproducible end result. This is similar to chroot but container allow you to do further with different o/s.

application on legacy database

sometime when we migrate development server to the latest o/s but however it break the legacy application or its dependency, example database. In such a case, docker can come to the rescue, you can install legacy database in the docker container whilst the application still can access the database without any puzzle or not expected result. This is even more true when you are busy and focus on upgrading the development server, you don't have the time to upgrade the application or its database. When you are done develop development server, you can then upgrade the database to another version inside docker. I think docker in this case is a really good fit.

quick test for code

Many times when you write bash script, you want to quickly test if the script works fine. But you don't want to test run on your machine as it will change the underlying configuration/state. If you run a container, those code can be quickly test it and when you are done, you can exit the container and nothing harmful done to the host. In this case, you are totally sure your code is tested well and in the same time with less maintenance after tests.

That's it I want to share my opinions and use cases for docker container. If I learn new way of using docker, I will update this document. I hope you will find it useful for your use cases.

Friday, June 25, 2021

How to cherry pick on a commit but only a few files from upstream patch

I forked a repository from upstream and there was a patch I like and I would like that patch goes into my forked repository. But at the same time, I would like to pick only a few changes, that is, not the whole commit and at the same time too, I need to make some minor modifications. So here goes how this is done.

Let's check where we are at now.

 jason@localhost:~/advanced-policy-firewall$ git branch  
 * master  

Get the commit id from roberto patch, cherry pick the whole commit but do not commit yet.. just stage at the current branch (which is master)

 jason@localhost:~/advanced-policy-firewall$ git cherry-pick -n 0d1df6549820f9592aefb2353b77c52eadbe759f  
 Auto-merging files/vnet/vnetgen  
 CONFLICT (content): Merge conflict in files/vnet/vnetgen  
 error: could not apply 0d1df65... - fixed vnetgen for newer linux distros to prioritize ip over ipconfig  
 hint: after resolving the conflicts, mark the corrected paths  
 hint: with 'git add <paths>' or 'git rm <paths>'  
 jason@localhost:~/advanced-policy-firewall$ git status .  
 On branch master  
 Your branch is up to date with 'origin/master'.  
 Changes to be committed:  
  (use "git restore --staged <file>..." to unstage)  
      modified:  README  
      new file:  test/distros_examples/ifconfig_ubuntu_12  
      new file:  test/distros_examples/ifconfig_ubuntu_20  
      new file:  test/distros_examples/ip_addr_ubuntu_12  
      new file:  test/distros_examples/ip_addr_ubuntu_20  
      new file:  test/distros_examples/ip_link_ubuntu_12  
      new file:  test/distros_examples/ip_link_ubuntu_20  
 Unmerged paths:  
  (use "git restore --staged <file>..." to unstage)  
  (use "git add <file>..." to mark resolution)  
      both modified:  files/vnet/vnetgen  

Let's get the diff of the stage file

 jason@localhost:~/advanced-policy-firewall$ git diff --cached README  
 diff --git a/README b/README  
 index 07ad004..0adf39d 100644  
 --- a/README  
 +++ b/README  
 @@ -199,7 +199,7 @@ Fedora Core Any  
  Slackware 8.0+  
  Debian GNU/Linux 3.0+  
  Suse Linux 8.1+  
 -Unbuntu Any  
 +Ubuntu Any  
  TurboLinux Server 9+  
  TurboLinux Fuji (Desktop)  
  RedHat Linux 7.3,8,9  

Unstage a file because I wanna make minor modification. After changes are make, add it back to the stage

 $ git restore --staged test/distros_examples/ip_link_ubuntu_12  
 $ vim test/distros_examples/ip_link_ubuntu_12  
 $ git add test/distros_examples/ip_link_ubuntu_12  

All good now, let's commit

 $ git commit -m "cherry pick but only selected files from roberto patched"  
 [master 80830c9] cherry pick but only selected files from roberto patched  
  8 files changed, 330 insertions(+), 28 deletions(-)  
  create mode 100644 test/distros_examples/ifconfig_ubuntu_12  
  create mode 100644 test/distros_examples/ifconfig_ubuntu_20  
  create mode 100644 test/distros_examples/ip_addr_ubuntu_12  
  create mode 100644 test/distros_examples/ip_addr_ubuntu_20  
  create mode 100644 test/distros_examples/ip_link_ubuntu_12  
  create mode 100644 test/distros_examples/ip_link_ubuntu_20  
 $ git branch  
 * master  

and we push the changes to github

 $ git push  
 Enumerating objects: 19, done.  
 Counting objects: 100% (19/19), done.  
 Delta compression using up to 16 threads  
 Compressing objects: 100% (13/13), done.  
 Writing objects: 100% (14/14), 3.68 KiB | 3.68 MiB/s, done.  
 Total 14 (delta 7), reused 0 (delta 0), pack-reused 0  
 remote: Resolving deltas: 100% (7/7), completed with 4 local objects.  
   f98e9bb..80830c9 master -> master  

in case you want to see the final result, please visit this github commit.

Monday, June 21, 2021

Continuous Integration with GitHub Action

This is a contribution to the SUSE Cloud Native Foundations Scholarship Program which I received and some of the peers want a CI online demo. So here I will share on my knowledge and experience on continuous integration using a public repository and public runner. I will start with a sample project creation, GitHub project setup and end with GitHub action setup and runner. 

What is CI? 

In software engineering, continuous integration (CI) is the practice of merging  all developers' working copies to a shared mainline several times a day.[1]

So essentially, it is a routine where every developer has to go through after they made code changes. Example, syntax check, linting, code compiling, multiple tests, package building, perhaps also support different runtime versions and/or operating systems.

There are many CI software available, please choose the one which match your requirements. I particularly like Jenkins a lot but Jenkins would require you to setup the runner on your machine. Since the objective of this blog is all public, hence, I picked GitHub action.

Let's begin with initial project setup. Reference if you want to know more.


$ export JAVA_HOME=/usr/lib/jvm/jdk-11.0.5/

$ mvn --version

Apache Maven 3.6.3

Maven home: /usr/share/maven

Java version: 11.0.5, vendor: Oracle Corporation, runtime: /usr/lib/jvm/jdk-11.0.5

Default locale: en_US, platform encoding: UTF-8

OS name: "linux", version: "5.10.0-7-amd64", arch: "amd64", family: "unix"

$ mvn archetype:generate -DartifactId=demo_ci -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false

[INFO] Scanning for projects...


[INFO] ------------------< org.apache.maven:standalone-pom >-------------------

[INFO] Building Maven Stub Project (No POM) 1

[INFO] --------------------------------[ pom ]---------------------------------



[INFO] ------------------------------------------------------------------------


[INFO] ------------------------------------------------------------------------

[INFO] Total time:  5.555 s

[INFO] Finished at: 2021-06-20T14:53:50+08:00

[INFO] ------------------------------------------------------------------------

$ cd demo_ci

$ tree .


├── pom.xml

└── src

    ├── main

    │   └── java

    │       └── ch

    │           └── weetech

    │               └── app

    │                   └──

    └── test

        └── java

            └── ch

                └── weetech

                    └── app


11 directories, 3 files

$ mvn package

[INFO] Scanning for projects...


[INFO] -----------------------< >-----------------------

[INFO] Building demo_ci 1.0-SNAPSHOT

[INFO] --------------------------------[ jar ]---------------------------------


[INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ demo_ci ---

[INFO] Using 'UTF-8' encoding to copy filtered resources.




[INFO] ------------------------------------------------------------------------


[INFO] ------------------------------------------------------------------------

[INFO] Total time:  2.221 s

[INFO] Finished at: 2021-06-20T14:56:41+08:00

[INFO] ------------------------------------------------------------------------

$ java -cp target/demo_ci-1.0-SNAPSHOT.jar

Hello World!


Once we have the sample project setup, test and compile code locally okay. Then it is time that we initialize git repository locally and push to GitHub. But before  we do of the following, you need to create a new repository on your GitHub.


$ mvn clean

[INFO] Scanning for projects...


[INFO] -----------------------< >-----------------------

[INFO] Building demo_ci 1.0-SNAPSHOT

[INFO] --------------------------------[ jar ]---------------------------------

[INFO] ------------------------------------------------------------------------


[INFO] ------------------------------------------------------------------------

[INFO] Total time:  2.079 s

[INFO] Finished at: 2021-06-20T15:24:46+08:00

[INFO] ------------------------------------------------------------------------

$ git init 

hint: Using 'master' as the name for the initial branch. This default branch name

hint: is subject to change. To configure the initial branch name to use in all

hint: of your new repositories, which will suppress this warning, call:


hint: git config --global init.defaultBranch <name>


hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and

hint: 'development'. The just-created branch can be renamed via this command:


hint: git branch -m <name>

$ git status -m master

$ git status .

On branch master

No commits yet

Untracked files:

  (use "git add <file>..." to include in what will be committed)



nothing added to commit but untracked files present (use "git add" to track)

$ git add pom.xml src/

$ git commit -m "initial"

[master (root-commit) 2cd8641] initial

 3 files changed, 108 insertions(+)

 create mode 100644 pom.xml

 create mode 100644 src/main/java/ch/weetech/app/

 create mode 100644 src/test/java/ch/weetech/app/

$ git remote add origin

$ git branch -M main

$ git push -u origin main

Enumerating objects: 16, done.

Counting objects: 100% (16/16), done.

Delta compression using up to 16 threads

Compressing objects: 100% (6/6), done.

Writing objects: 100% (16/16), 1.76 KiB | 899.00 KiB/s, done.

Total 16 (delta 0), reused 0 (delta 0), pack-reused 0


 * [new branch]      main -> main

Branch 'main' set up to track remote branch 'main' from 'origin'.

$ git status .

On branch main

Your branch is up to date with 'origin/main'.

nothing to commit, working tree clean


Now that you pushed everything to GitHub, next is to setup GitHub Actions.

1. Locate Actions from the project tab.

2. Picked 'Java with Maven' as this best match the current requirement.

3. Check action configurations are okay and commit it. 

4. once you commit, the action will kickstart the first run.

Congratulation! This is the first CI that you setup. The rest, as you may have already guessed will be the same as every developer will do, i.e. making code changes.


$ vim

$ cat

a contribution to

$ git status .

On branch main

Your branch is up to date with 'origin/main'.

Untracked files:

  (use "git add <file>..." to include in what will be committed)

nothing added to commit but untracked files present (use "git add" to track)

$ git add 

$ git commit -m "added readme" 

[main a966f09] added readme

 1 file changed, 1 insertion(+)

 create mode 100644

$ git push

Enumerating objects: 4, done.

Counting objects: 100% (4/4), done.

Delta compression using up to 16 threads

Compressing objects: 100% (3/3), done.

Writing objects: 100% (3/3), 410 bytes | 410.00 KiB/s, done.

Total 3 (delta 0), reused 0 (delta 0), pack-reused 0


   a273126..a966f09  main -> main


That's it, in case you figure where can I find this repository to begin mine? 

Friday, December 18, 2020

OpenHAB vs Xiaomi Sensor

original from 

Some time ago I started to use OpenHAB to expand the monitoring of my servers to the whole apartment. It would be nice to know whether I closed the freezer in the basement again or if I left the door open out of sheer senility. Corresponding sensors are available for relatively little money, e.g. from Xiaomi (or from other manufacturers for a lot more money, whether they are easier to integrate is the big question). However, the integration of the Xiaomi sensors in OpenHAB is a Chinese opera in several acts: 

 Act 1: The starter set The starter set is available for around 80.- and it comes with a pressure switch, two door sensors and two motion detectors as well as the base station. According to the description, everything is very simple: Start the base station, install the Mihome app on an Android phone, select "Mainland China" as the server location, connect the app to the base station, activate developer mode via a hidden menu, read out the key and so that the base station can be integrated into OpenHAB. Then everything would be very easy with a data flow sensor -> Xiaomi Hub -> OpenHAB. Yes but... Exactly, because the whole thing only works with the "Mainland China Edition" base station, which is not available in Europe. You can presumably have them delivered overseas through a Chinese wholesaler (don't forget the travel adapter, Chinese plugs don't fit into European sockets). But the EU edition is unusable: - If you select "Mainland China" as the server location in the app, the base station cannot be found and therefore cannot be connected - If you choose the server location "Europe", the hidden menu to activate the developer mode is missing. 

 Act 2: Obsolete app With a little research it turned out that an outdated version of the Mihome app can be found on dubious pages, which contains an error: It writes a debug log. Where to find the access key. Unfortunately, that alone doesn't help. This allows you to integrate the hub via the Xiaomi Mi IO extension from OpenHAB. But that was all. As a result, there is still no access to the sensors. For this, the developer mode would still have to be activated, which also opens Telnet access on the device. Now there are two more options: A modified Mihome app from a Russian website that is completely in Cyrillic. Well uh ... Njet! Or unpack the soldering iron, tap the serial port, use it to gain terminal access and activate the Telnet server. Now that there is a good chance that this can destroy the device, I prefer to leave it (for now). At least I could resell it while it still works. 

 Act 3: The Aqara Hub A further look at the documentation of the Mihome binding shows: The hub in version 3 (which is available as Aqara Hub for Apple Homekit) should be a little more accessible. Unfortunately, that costs almost as much as the whole set. And then just as little can. I immediately sent it back accordingly ...

Act 4: Cheap Zigbee Stick
The Xiaomi devices, like all proprietary garbage, of course never exactly adhere to the standards. But at least enough that the protocol just barely passes as Zigbee. So I bought a USB Zigbee stick from the richest man in the world for € 9 + € 3.50 shipping. To my great surprise, this, although electronic device, it was sent from amazon germany to switzerland. Very unusual. And arrived super fast too. Also unusual.

It is a simple USB stick with a CC2531 chip and zigbee2mqtt-compatible firmware preinstalled. Very awesome!

In principle, OpenHAB would be able to address the Zigbee stick directly via the Zigbee binding. The data flow would then be Sensor -> USB stick -> OpenHAB. But there was something with the protocol standard at Xiaomi and stick to it. The sensors can be integrated, but are displayed as "offline" and no status can be queried. As usual, the following applies: why easy when it can be complicated?

Now the from-behind-through-the-chest-in-the-eye installation for the data flow sensor -> USB stick -> zigbee2mqtt -> mqtt-broker -> OpenHAB begins.
First the stick is connected, it is recognized as a USB serial device / dev / ttyACM0.
Now an MQTT broker has to be installed, e.g. mosquitto from the Debian package sources. This is started without further configuration.
Next, zigbee2mqtt is installed with what feels like two thousand Node.JS dependencies (including npm from the Debian backports if you use Debian Stable as a base). In contrast to the OpenHAB part that follows later, this is excellently documented, so that this part feels more like paint-by-numbers than system administration.

In principle, the devices can now be integrated. Simply reset the sensor with the SIM pin included in the package, and that's it. According to the instructions, you may have to repeat the process several times, but with the first two sensors it worked right away. A look at journalctl -u zigbee2mqtt -f shows activity.

Now comes the hard part: connecting OpenHAB to MQTT. This is documented very superficially and abstractly. Add to this the chaos with instructions for MQTT1 and MQTT2 binding when you google for solutions. Which now applies to my installation? Boh? Ultimately, I followed the instructions for MQTT2, and that worked at some point. Probably: MQTT1 == OpenHAB1, MQTT2 == OpenHAB2 (and I'm running 2.5).

How to proceed:
In the zigbee2mqtt configuration file /opt/zigbee2mqtt/data/configuration.yaml, the output should not be output as JSON but as an attribute. To do this, insert the following lines, save, restart zigbee2mqtt:

    output: attribute

And if we are already fiddling with the configuration, one should also assign sensible friendly_name to the sensors.
First install the MQTT binding in OpenHAB.
Then create a .things file with the required entries in /etc/openhab2/things /. At some point I found halfway suitable instructions in the forum ...
And now you are surprised that the things appear in the GUI, but no data is read ... Signal strength? NaN. Battery level? NaN. Status? Off. grrrmpf. After a long debugging process (yes, zigbee2mqtt writes in mosquitto, you can read along with mosquitto_sub -v -t '#') at some point just triggered the spontaneous Windows reflex and restarted OpenHAB itself. Aaand! Bingo! Everything works. So easy! Incidentally, the restart is necessary for every newly added (or renamed) device.

The finale: the OpenHAB Things file

Bridge mqtt:broker:MosquittoMqttBroker "Mosquitto MQTT Broker" [ host="", secure=false] {
Thing topic xdoor1 "Xiaomi Door Sensor" @ "Location" {
Type switch : contact "contact" [ stateTopic = "zigbee2mqtt/xdoor1/contact", on="true", off="false" ]
Type number : voltage "voltage" [ stateTopic = "zigbee2mqtt/xdoor1/voltage" ]
Type number : battery "battery" [ stateTopic = "zigbee2mqtt/xdoor1/battery" ]
Type number : linkquality "linkquality" [ stateTopic = "zigbee2mqtt/xdoor1/linkquality" ]

Additional sensors can now easily be added to the bridge block. With a little more typing, sensors can also be defined outside the bridge block:

Thing mqtt:topic:MosquittoMqttBroker:BodySensor "Xiaomi Body Sensor" (mqtt:broker:MosquittoMqttBroker) @ "Location" {
Type switch : occupancy "occupancy" [ stateTopic = "zigbee2mqtt/xbody1/occupancy", on="true", off="false" ]
Type number : voltage "voltage" [ stateTopic = "zigbee2mqtt/xbody1/voltage" ]
Type number : battery "battery" [ stateTopic = "zigbee2mqtt/xbody1/battery" ]
Type number : linkquality "linkquality" [ stateTopic = "zigbee2mqtt/xbody1/linkquality" ]

The existing channels can be found out via mosquitto_sub or journalctl. As soon as you stimulate a sensor, it sends all of this information to the Zigbee controller.

Of course, especially in combination with Zigbee (or Z-Wave), OpenHAB is a bottomless pit in terms of possibilities. A lot of technology can be connected even without a wireless connection: printers, mail and XMPP accounts, WLAN (or connected devices), telephone systems, mpd (Music Player Daemon), video cameras (e.g. via Zoneminder - but that would be a blog entry in itself) . With Zigbee everything gets even wilder. After the sensors, the entire rest of the house can be integrated, from lamps, heating and roller shutter control to the washing machine to the lawn mower to the wallbox of the electric vehicle.
If more Zigbee sensors / actuators are to be set up a little further away, you simply take a Raspberry Pi, connect another USB stick to it, install zigbee2mqtt and have the sensor data sent over the network to the MQTT broker on the OpenHAB machine .

Thursday, November 26, 2020

How does Reverse DNS work behind the scene - a layman explanation

Ever wonder what actually happen behind the scene when you do a reverse DNS query?

It is quick and it return a value.

 $ time dig -x +short  
 real     0m0.019s  
 user     0m0.005s  
 sys     0m0.005s

In this article, I will explain to you want happen behind the scene.

when the query pass to your resolver, what your resolver does, when you ask it for the ptr (which is )

 $ dig ptr  

which will tell them: "I don't know about - you need to ask the server" which correspond to

 ;; AUTHORITY SECTION:          172800     IN     NS          172800     IN     NS          172800     IN     NS          172800     IN     NS          172800     IN     NS          172800     IN     NS  

then the resolver asks one or more of them:

dig ns

again, it will get delegated to the next servers, which handle ""		86400	IN	NS		86400	IN	NS		86400	IN	NS		86400	IN	NS		86400	IN	NS		86400	IN	NS

the game continues:

dig ns

"you gotta ask level 3, they know about"	86400	IN	NS	86400	IN	NS

and the final delegation from level 3 is to the google nameservers:

dig ns


;; AUTHORITY SECTION:	3600	IN	NS	3600	IN	NS	3600	IN	NS	3600	IN	NS

and only from them will you get the final anser for

 dig PTR  
 ; <<>> DiG 9.10.6 <<>> PTR  
 ;; global options: +cmd  
 ;; Got answer:  
 ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20871  
 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1  
 ;; WARNING: recursion requested but not available  
 ; EDNS: version: 0, flags:; udp: 512  
 ;          IN     PTR  
 ;; ANSWER SECTION:     86400     IN     PTR  
 ;; Query time: 132 msec  
 ;; SERVER: 2001:4860:4802:32::a#53(2001:4860:4802:32::a)  
 ;; WHEN: Thu Nov 26 10:53:58 CET 2020  
 ;; MSG SIZE rcvd: 73  

That's it!