Re: DNS and subdomains

Given "cat.p.dirtside.com", to argue that "p.dirtside.com" is not a domain of which "cat.p.dirtside.com" is a sub-domain, is to claim, that “cat.p” is a single token. This is no more true than claiming a series of words with spaces can be a single word. It doesn’t matter if I think, want or inte

Re: DNS and subdomains

On Fri, Feb 28, 2025 at 3:18 PM, William Herrin wrote: > On Fri, Feb 28, 2025 at 9:11 AM Jay wrote: > > Every subdomain is in fact a domain name. > > Hi Jay, > > Not necessarily. > > Remember my example cat.p.dirtside.com? P.dirtside.com > is a subdomain of dirtside.com.

Re: DNS and subdomains

On Fri, Feb 28, 2025 at 12:50 PM David Conrad wrote: > On Feb 28, 2025, at 12:18 PM, William Herrin wrote: > > Remember my example cat.p.dirtside.com? P.dirtside.com is a subdomain > > of dirtside.com. It's an administrative grouping of domain names that > > have a particular characteristic. Howe

Re: DNS and subdomains

Bill, On Feb 28, 2025, at 12:18 PM, William Herrin wrote: > Remember my example cat.p.dirtside.com? P.dirtside.com is a subdomain > of dirtside.com. It's an administrative grouping of domain names that > have a particular characteristic. However, p.dirtside.com is NOT a > domain name. It has no D

Re: DNS and subdomains

On Fri, Feb 28, 2025 at 9:11 AM Jay wrote: > Every subdomain is in fact a domain name. Hi Jay, Not necessarily. Remember my example cat.p.dirtside.com? P.dirtside.com is a subdomain of dirtside.com. It's an administrative grouping of domain names that have a particular characteristic. However,

Re: DNS and subdomains

On Fri, Feb 28, 2025 at 12:18 PM Harry Hoffman via NANOG wrote: > This is exactly the logic that I was operating under: A.B.EXAMPLE.COM > . is a subdomain, but it should never be > referred to > as a subdomain of EXAMPLE.COM . It is only a > subdom

Re: DNS and subdomains

Heya, Shumon! Great to hear from you and thanks for adjusting my understanding. It's also a good reminder to go read the RFCs so that I can eliminate assumptions :-) Cheers, Harry On Fri, Feb 28, 2025 at 12:29 PM Shumon Huque wrote: > On Fri, Feb 28, 2025 at 12:18 PM Harry Hoffman via NANOG >

Re: DNS and subdomains

This is exactly the logic that I was operating under: A.B.EXAMPLE.COM . is a subdomain, but it should never be referred to as a subdomain of EXAMPLE.COM . It is only a subdomain of B.EXAMPLE.COM . On Fri, Feb 28, 2025 at 12:11

Re: DNS and subdomains

On Fri, Feb 28, 2025 at 10:05 AM Stephane Bortzmeyer via NANOG wrote: > On Tue, Feb 25, 2025 at 07:36:16AM -0500, Yes. I believe the confusion is that some documentation, APIs, or software incorrectly obfuscate the concept of a domain and take that the domain is only the part registered with a d

Re: DNS and subdomains

On Tue, Feb 25, 2025 at 07:36:16AM -0500, Harry Hoffman via NANOG wrote a message of 168 lines which said: > I had a thought similar to what Bill describes, that everywhere there's a > dot (.) there's a subdomain. This is true. But a sub-domain is not always delegated (not every domain is a z

Re: DNS and subdomains

Thanks everyone for the wonderful answers! The thoughts in my head were not aligned with reality ;-) I had a thought similar to what Bill describes, that everywhere there's a dot (.) there's a subdomain. I also had the thought/assumption that the data to the left of the leftmost dot (.) was essent

Re: DNS and subdomains

On Mon, Feb 24, 2025 at 08:58:48PM -0500, Harry Hoffman via NANOG wrote a message of 195 lines which said: > Has this become common practice? Is there a definitive way to determine > subdomains? I seem to recall that "older" dns server software wouldn't > allow this but it could be that my mem

Re: DNS and subdomains

On Mon, Feb 24, 2025 at 5:58 PM Harry Hoffman via NANOG wrote: > In working with several OSINT sources for domain processing it seems like the > way domains and subdomains are processed essentially equates subdomains with > FQDNs. Hi Harry, I don't understand what you mean. Do you mean how do

Re: DNS and subdomains

Every domain is a subdomain of something else other than the root. access.api.bbc.com is a subdomain of api.bbc.com and a subdomain of bbc.com and a subdomain of com and a subdomain of . (the root). All subdomains are domains. All domains can have subdomains except those that are maximal size a

Re: DNS and subdomains

Most security tools, browsers included, use the boundaries from https://publicsuffix.org/ . While DNS could indicate what is a zone cut and what is not, it's not the only feature that indicates a transition between administrations. Rubens On Mon, Feb 24, 2025 at 10:59 PM Harry Hoffman via NANOG

DNS and subdomains

Hi Folks, Feel free to tell me this isn't the proper place for my question but given that networking and DNS are hand in hand I thought it might be reasonable to ask here. In working with several OSINT sources for domain processing it seems like the way domains and subdomains are processed essent