DNS: Notes

Domain Name System

DNS uses UDP port 53 as default and TCP port 53 as fallback.

nslookup

nslookup -type=txt youtube.com
nslookup -type=mx google.com

dig

dig youtube.com txt

host - DNS lookup utility

host -t txt google.com

Check PTR text record

PS C:\Users\Administrator> nslookup -type=ptr 173.82.240.78
Server:  UnKnown
Address:  2402:800:20ff:6666::1

Non-authoritative answer:
78.240.82.173.in-addr.arpa      name = mx2.practicehabits.net
PS C:\Users\Administrator>

Check DMARC text record

PS C:\Users\Administrator> nslookup -type=txt _dmarc.practicehabits.net
Server:  UnKnown
Address:  2402:800:20ff:6666::1

Non-authoritative answer:
_dmarc.practicehabits.net       text =

        "v=DMARC1; p=reject; rua=mailto:postmaster@practicehabits.net, mailto:postmaster@practicehabits.net"
PS C:\Users\Administrator> nslookup -type=txt _dmarc.2practice.xyz
Server:  UnKnown
Address:  2402:800:20ff:6666::1

*** No text (TXT) records available for _dmarc.2practice.xyz

Online tools

https://mxtoolbox.com/

https://ViewDNS.info/

DMARC Record Checker

DKIM Record Checker

DNS History Lookup

References

Practice

>>> THM | DNS Manipulation

>>> THM | DNS in Details

Qubes OS: Fedora 30

Create a new Standalone VM based on fedora-29 VM template Extend root partition: run command on dom0 tuyen@dom0:~ $ qvm-volume extend fedora-30:root 12288MB Set qrexec_timeout to 600 seconds tuyen@dom0:~ $ qvm-pref --set fedora-30 qrexec_timeout 600 $ sudo dnf upgrade --refresh $ sudo dnf install dnf-plugin-sytem-upgrade $ sudo dnf system-upgrade download --release=30 Install fedora-30 template Run the following command on dom0 terminal $ sudo qubes-dom0-update qubes-template-fedora-30 Install Adobe Flash Player Adobe Flash Player will not go away soon. So, let's grab the latest version of Adobe Flash Player , then install using yum or dnf command. Verify if Adobe Flash Player is installed and works by visiting https://helpx.adobe.com/flash-player.html [user@fedora-30 ~]$ sudo dnf install Downloads/flash-player-npapi-32.0.0.238-release.x86_64.rpm Last metadata expiration check: 0:37:03 ago on Fri Aug 30 09:18:10 2019. Dependencies resolved. =========...

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First of all, check BIOS Settings of your laptop or desktop Dell Look for USB PowerShare BIOS Settings: USB PowerShare Lenovo Look for Always On USB Charge in Off Mode BIOS Settings: Enable Always On USB Charge in Off Mode

Python: Free Online Courses

Ever thinking about which programming language to learn first? You can learn Python for free with these online courses.

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