Tech/Protocols/DNS
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Domain Name System
Domain Name System is a system/service that answers questions. Some may call it a directory service as that is very much like how it acts. The DNS idea was adopted by the industry in 1983[1] and still today is not understood by many.
Related
- Tech/Protocols/DNS/DNS Zone
- https://en.wikipedia.org/wiki/Domain_Name_System
- Tech/Protocols/DNS/DNS Checklist
- Tech/Protocols/DNS/DNS Resolvers
- Tech/Protocols/DNS/DNS resolver in systemd
- Tech/Basics/FQDN
- Tech/HowTo/Resetting DNS SOA Serial
- Tech/HowTo/Serving a CNAME at the apex
- Case Sensitive answers https://tools.ietf.org/html/rfc4343
Using Dig
Dig is the CLI tool to query DNS entries
Confirm the reverse delegation for a network
$ dig +short in ns 1.113.190.in-addr.arpa. dns1.tecnoera.com. dns2.tecnoera.com. dns5.tecnoera.com. dns6.tecnoera.com.
Check the version of software running on the nameserver
Mentioned in https://www.rfc-editor.org/rfc/rfc4892.html server admins may enable queries for items like version and ID
$ dig +short @a3-67.akam.net version.server chaos txt "33835.4" $ dig +short @dns1.tecnoera.com version.bind chaos txt "9.7.3" $ dig +short @a3-67.akam.net id.server chaos txt "33835.7"
Tracing the delegation path
$ dig +trace @8.8.4.4 in ns 4.113.190.in-addr.arpa. ; <<>> DiG 9.11.5-P4-5.1+deb10u2-Debian <<>> +trace @8.8.4.4 in ns 4.113.190.in-addr.arpa. ; (1 server found) ;; global options: +cmd . 85874 IN NS c.root-servers.net. . 85874 IN NS m.root-servers.net. . 85874 IN NS a.root-servers.net. . 85874 IN NS k.root-servers.net. . 85874 IN NS j.root-servers.net. . 85874 IN NS b.root-servers.net. . 85874 IN NS l.root-servers.net. . 85874 IN NS e.root-servers.net. . 85874 IN NS i.root-servers.net. . 85874 IN NS d.root-servers.net. . 85874 IN NS h.root-servers.net. . 85874 IN NS g.root-servers.net. . 85874 IN NS f.root-servers.net. . 85874 IN RRSIG NS 8 0 518400 20201201220000 20201118210000 26116 . hBBvYAd51gQ8SfulmkQ2zUl/CcoHlop4RU0QB2BWXevPysRsjc47Redv BNypY4uuI+IsI09VywdgRoWyIsl7+a74a5nFTpAJbVho5aLtxX2MgTxb 5lIqIXNffN/aC6EfGqq7ERumuTl7ET9ejrk4iVQEX4CqXZDtgodsp8Vj 4ufG9dlLgfMTO9UFrACygLuU54z9egvtuFOf26Qstppg6rtH0F6JfD05 IRHalrc6Ml9OPMH1hnPjSw7t/o1DVGA1D+CmXm4G1xZ+dmFzmQWcmMiG ed5bXbSMZIQWvpBy4LRv0HYsLwsAloKD+xQwmHgR01Kn++jKYTsyc+g9 D2KC7A== ;; Received 525 bytes from 8.8.4.4#53(8.8.4.4) in 11 ms in-addr.arpa. 172800 IN NS a.in-addr-servers.arpa. in-addr.arpa. 172800 IN NS b.in-addr-servers.arpa. in-addr.arpa. 172800 IN NS c.in-addr-servers.arpa. in-addr.arpa. 172800 IN NS d.in-addr-servers.arpa. in-addr.arpa. 172800 IN NS e.in-addr-servers.arpa. in-addr.arpa. 172800 IN NS f.in-addr-servers.arpa. in-addr.arpa. 86400 IN DS 47054 8 2 5CAFCCEC201D1933B4C9F6A9C8F51E51F3B39979058AC21B8DF1B1F2 81CBC6F2 in-addr.arpa. 86400 IN DS 53696 8 2 13E5501C56B20394DA921B51412D48B7089C5EB6957A7C58553C4D4D 424F04DF in-addr.arpa. 86400 IN DS 63982 8 2 AAF4FB5D213EF25AE44679032EBE3514C487D7ABD99D7F5FEC3383D0 30733C73 in-addr.arpa. 86400 IN RRSIG DS 8 2 86400 20201202120000 20201119110000 4825 arpa. z/GDbJKy7doBIjenXeys66fKgkzh5MIL/Pl5gCwZGjHseR9NtGp46+Mb 3jypFZAmJdpUL4LXMJQnrhRxb/Kc9VNe17SnNKlStypBGetLTJ6srs5Y IEzZhejnRq1RwkWOGyIWC7Thgi0s8eJ+VHcT5/dIAl0dN2vuFpxGR6Ka B3mSa+LyUWbgKwH/PKpSh+zhgZWZJILIMZQef/jebsII7vOlxLmd6ulR y6D97pak+SeCu/81RThta/zGJzhpfW6u3hp/H6iYwnfkOT2sTbrQhoCU oJAle4RuTPD6iU3dyrbSkuqZXrUThwVA1+rJhlCENLKVZ2IFjBb0HLp9 Gzdvgg== ;; Received 863 bytes from 199.7.83.42#53(l.root-servers.net) in 10 ms 190.in-addr.arpa. 86400 IN NS ns3.afrinic.net. 190.in-addr.arpa. 86400 IN NS ns.lacnic.net. 190.in-addr.arpa. 86400 IN NS a.arpa.dns.br. 190.in-addr.arpa. 86400 IN NS a.lactld.org. 190.in-addr.arpa. 86400 IN NS ns4.apnic.net. 190.in-addr.arpa. 86400 IN NS lacnic.authdns.ripe.net. 190.in-addr.arpa. 86400 IN NS tinnie.arin.net. 190.in-addr.arpa. 86400 IN NS ns-lacnic.nic.mx. 190.in-addr.arpa. 86400 IN NS ns2.lacnic.net. 190.in-addr.arpa. 86400 IN DS 32020 8 1 CA181AE662A2ACF8100340B2785A3314BA4E963B 190.in-addr.arpa. 86400 IN DS 32020 8 2 3C750A4E1E0ED9673AB120F006800CB8AF4BB303F394BA904CE601DF B7439DB1 190.in-addr.arpa. 86400 IN RRSIG DS 8 3 86400 20201130161510 20201109070002 39481 in-addr.arpa. pGuKQOHCfrw3D4/mwKPFbOQCbYLrKIxqJl+cvXet8qoZRv/eZuAoM2NA LQ9bq7VxEAe9YxR2jc48iwq3EZBCLEZXiUaKa+W6gARGNDY3AI+jlotW Kwh4392e00JKMa4MZ0j/PFgpelP0Cf4espXvGL6N3SUyiI56kjt2jyD+ lbo= ;; Received 601 bytes from 203.119.86.101#53(e.in-addr-servers.arpa) in 146 ms 4.113.190.in-addr.arpa. 86400 IN NS DNS2.TECNOERA.COM. 4.113.190.in-addr.arpa. 86400 IN NS DNS5.TECNOERA.COM. 4.113.190.in-addr.arpa. 86400 IN NS DNS6.TECNOERA.COM. 4.113.190.in-addr.arpa. 86400 IN NS DNS1.TECNOERA.COM. 4.113.190.in-addr.arpa. 10800 IN NSEC 5.113.190.in-addr.arpa. NS RRSIG NSEC 4.113.190.in-addr.arpa. 10800 IN RRSIG NSEC 8 5 10800 20201206125538 20201106124223 4965 190.in-addr.arpa. mq0In8JRBYaYXnOjkrD/RGa+5LceZJliNWXD3l5Ow5y86G/3+5HBg3Xz 8G9wjmTr8bJo5icljGFjNnzDpP3sHHxkBKxXSj7DhpGsxj3FA19sZ9gl I7ItGOMDg5fs7Wrex6TbBH963XgUZcN/J3pyYK43IKtp0JXN23/7jFRw DozH6GJkFPmAhgZ00aIT/3KzDg2HNk30KLUNmDJiiwPrVHcYBeA9vS/g 3vTyH/x5ukICSpdi+R+pDwZ+CDWftwgdcZVtuWM5xbm5LSZDFnO3PMCl /QYcV+NVMSnLV2zd4d4JO5zSTqGlbtZmQPOQFcsKsE6ZFTuvYll4SNGo GB2rCw== ;; Received 487 bytes from 2001:67c:e0::11#53(lacnic.authdns.ripe.net) in 119 ms 4.113.190.in-addr.arpa. 300 IN NS DNS2.TECNOERA.COM. 4.113.190.in-addr.arpa. 300 IN NS DNS5.TECNOERA.COM. 4.113.190.in-addr.arpa. 300 IN NS DNS6.TECNOERA.COM. 4.113.190.in-addr.arpa. 300 IN NS DNS1.TECNOERA.COM. ;; Received 203 bytes from 200.24.224.80#53(DNS5.TECNOERA.COM) in 163 ms
- Dig with Xargs
$ dig +short gringomalvado.com NS | xargs -I x dig +noall +answer +ttlid ipv6.gringomalvado.com AAAA @x ipv6.gringomalvado.com. 600 IN AAAA 2600:3c00::f03c:91ff:fed1:fe55 ipv6.gringomalvado.com. 600 IN AAAA 2600:3c00::f03c:91ff:fed1:fe55 ipv6.gringomalvado.com. 600 IN AAAA 2600:3c00::f03c:91ff:fed1:fe55 ipv6.gringomalvado.com. 600 IN AAAA 2600:3c00::f03c:91ff:fed1:fe55
DKIM
DomainKeys Identified Mail (DKIM) are TXT RRs that using a selector from the email header verify against impersonation.
[emailheaderselector]._domainkey.[domainname]