How do i know if example.com is delegating example.mydomain.com to its own zone?

Peter Smith

7/30/23, 3:47 PM

An additional question is, can I find out what zones example.com is delegating to?

This all assumes I am not an Admin for any of the sites/zones in question -- I'm just on the public internet, these are public-facing servers/zones, etc.

If i know that foo.example.com exists, and it has an SOA record, does that mean that it is being delegated to, by definition? (assuming it's not configured incorrectly)

so if I query a domain for NS records, and they show up, then, by definition, those are the authoritative name servers for that domain?

me@WIN-0G109DMKIEK:~$ dig NS example.com +short b.iana-servers.net. a.iana-servers.net.

0 + 0

domain-name-system

delegation

Score:2

Server

Patrick Mevzek

7/30/23, 4:02 PM

By definition, a delegation means NS records.

So check if foo.example.com has NS records on authoritative nameservers for example.com.

The NS records will show, if there, the authoritative nameservers for the subdomain.

This works the same way at all level of the DNS tree, here showing the delegation from com to example.com:

$ dig NS @$(dig NS com +short | head -1) example.com +noall +auth
example.com.        2d IN NS a.iana-servers.net.
example.com.        2d IN NS b.iana-servers.net.

If i know that foo.example.com exists, and it has an SOA record, does that mean that it is being delegated to, by definition? (assuming it's not configured incorrectly)

The SOA in the child is technically also a proof of delegation, normally. To be 100% correct you need more than that to check the delegation point or cut zone case, at the parent, and if it has NS records.

0 + 0

Peter Smith

7/30/23, 7:46 PM

so if I query a domain for NS records, and they show up, then, by definition, those are the authoritative name servers for that domain? `me@WIN-0G109DMKIEK:~$ dig NS example.com +short b.iana-servers.net. a.iana-servers.net.`

Patrick Mevzek

7/30/23, 8:16 PM

You need to ask the authoritative servers where you think the delegation happens, so you need the `@` option, see my example. But the `NS` records are designing who are the authoritative nameservers for that delegation, yes.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How do i know if example.com is delegating example.mydomain.com to its own zone?

TH: ฉันจะรู้ได้อย่างไรว่า example.com กำลังมอบหมายสิทธิ์ให้ example.mydomain.com อยู่ในโซนของตัวเอง

RO: Cum știu dacă example.com deleagă example.mydomain.com în propria sa zonă?

RU: Как узнать, делегирует ли example.com example.mydomain.com свою собственную зону?

VI: Làm cách nào để tôi biết liệu example.com có đang ủy thác example.mydomain.com cho vùng riêng của mình không?

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