dns

unbound

/etc/unbound/unbound.conf.d/forward.conf
# unbound  forward-zone output
for IP in $(consul catalog nodes | grep ctl | cut -d " " -f6); do
    echo "  forward-addr: ${IP}@53"
done
systemctl restart unbound

# disable IPv6
# /etc/unbound/unbound.conf.d/server.conf 
server:
...
   do-ip6: no

# flush zone
unbound-control flush_zone dev.example.com

Links
https://wiki.alpinelinux.org/wiki/Setting_up_unbound_DNS_server
https://calomel.org/unbound_dns.html

dnsmasq

# cat /etc/dnsmasq.conf
dhcp-authoritative
server=192.168.1.6

log-facility=/var/log/dnsmasq.log
log-queries

local=/example.com/
domain=example.com

# cat /etc/dnsmasq.conf | grep "^dhcp-host" | awk -v OFS="\t" -F "," '{print $3, $2}' | sort  -k2 > /etc/hosts.pre
addn-hosts=/etc/hosts.pre

# DHCP
dhcp-range=192.168.1.150,192.168.1.200,255.255.255.0,1d
dhcp-option=option:router,192.168.1.6
dhcp-option=option:ntp-server,217.7.239.199

# DNS
dhcp-option=option:dns-server,1.1.1.1,8.8.8.8

# PXE
dhcp-boot=undionly.kpxe,srv,192.168.1.9
dhcp-boot=net:sip,http://srv/snom3x0/snom3x0.xml,srv,192.168.1.9
dhcp-boot=net:ts,ltsp/amd64/pxelinux.0,ts,192.168.1.159

# Clients
dhcp-host=00:00:00:00:00:03,www,192.168.1.3
dhcp-host=00:00:00:00:01:70,mx,192.168.1.170

# LTSP
dhcp-host=00:01:02:03:04:11,workstation1,192.168.1.79,net:ts
dhcp-host=00:01:02:03:04:22,workstation2,192.168.1.80,net:ts

dig

dig txt example.com @8.8.8.8
dig example.com | grep -v ";" | grep A
dig -x 8.9.10.11 | grep IN

DNS

# Get DNS resolv status
resolvectl status
systemd-resolve --status

# Flush DNS cache
sudo systemd-resolve --flush-caches

Flush DNS cache

sudo systemd-resolve --flush-caches

SystemV

# flush DNS
systemctl restart nscd

# resolvconf
sudo systemctl enable resolvconf

SPF
http://wiki.hetzner.de/index.php/DNS_SPF

DIG
https://www.cyberciti.biz/faq/linux-unix-dig-command-examples-usage-syntax/
https://intodns.com/

dig @10.0.0.22 -p 8500 +short A www1.example.com

DNSSEC
https://www.scip.ch/?labs.20140911
# validator
https://dnsviz.net/
https://dnssec-analyzer.verisignlabs.com/

Public recursive name server
https://en.wikipedia.org/wiki/Public_recursive_name_server

AdGuard free / public DNS filter
https://adguard.com/en/blog/adguard-dns-new-addresses.html

dns