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Ask HN: why are domain names reversely ordered?

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Re: Ask HN: why are domain names reversely ordered?

#11

Post by junklight »

tokenadult wrote: post #6
jacquesm wrote: post #3

This is widely considered to be a mistake.

This is widely considered to be a mistake. Citations, please? I've been able to deal with it over the years.

It turns out to be a complete pain for working out scope in Web crawlers because you need to separate the domain from the path part and deal with them separately. If it was in the opposite order it would be much simpler to process.

The Heritrix crawler (primarily worked on by the Internet Archive) introduces a "surt" form which is basically the domain in the same order as the path so that Reading from left to right it goes from least specific to most specific.

Re: Ask HN: why are domain names reversely ordered?

#12

Post by aristus »

It's just a convention, and one that took a while to work itself out. Some older mail servers used to route (and even rewrite -- shudder) domains the other way round. Like little- and big-endian numbers, the merits of either method are less important than having everyone do it the same way.

http://catb.org/jargon/html/B/big-endian.html

Re: Ask HN: why are domain names reversely ordered?

#13

Post by jacquesm »

junklight wrote: post #11
tokenadult wrote: post #6

Earlier quoted context omitted.

This is widely considered to be a mistake. Citations, please? I've been able to deal with it over the years.

It turns out to be a complete pain for working out scope in Web crawlers because you need to separate the domain from the path part and deal with them separately. If it was in the opposite order it would be much simpler to process. The Heritrix crawler (primarily worked on by the Internet Archive) introduces a "surt" form which is basically the domain in the same order as the path so that Reading from left to right i…

Crawling is an inconvenience, sure it is problematic, but phishing is much more problematic. You can train a machine to parse that thing right-to-left no problem, to tell users to start middle-to-left and then middle-to-right is too much of a burden.

Re: Ask HN: why are domain names reversely ordered?

#14

Post by spidaman »

I think everybody that has to write applications that deal with URLs as core identifiers have asked this. It's also hairy 'cause leading part of a URL (protocol and hostname) is case insensitive but the trailing part (path, query string and fragment) isn't. At my last job I created a framework for normalizing and canonicalizing URLs as well as storing them consistently (with the hostname components reversed), it was a big improvement for retrieval and duplication detection accuracy and performance.

Re: Ask HN: why are domain names reversely ordered?

#15

Post by jws »

I think it comes down to history. Host names existed before domain names. When domains were bolted on they used the idea of a default domain for each host and that made sense to be on the end.

Consider:

  telnet hosta          # established way
  telnet hosta.abc      # domain bolted on back
  telnet abc.hosta      # domain bolted on front
Since people knew the host names and were used to dealing with them, the suffix was more natural since it kept the domain cruft out at the edge.

Re: Ask HN: why are domain names reversely ordered?

#16

Post by s3graham »

I have no idea. UUCP (Usenet) addresses used to be (are?) "backwards" and ! separated. Maybe some historical references related to that would point you to more info.

If I were to guess though, I'd guess email addresses. me@machine being originally valid makes me@tld.machine harder to parse?

Re: Ask HN: why are domain names reversely ordered?

#17

Post by junklight »

jacquesm wrote: post #13
junklight wrote: post #11

Earlier quoted context omitted.

It turns out to be a complete pain for working out scope in Web crawlers because you need to separate the domain from the path part and deal with them separately. If it was in the opposite order it would be much simpler to process. The Heritrix crawler (primarily worked on by the Internet Archive) introduces a "surt" form which is basically the domain in the same order as the path so that Reading from left to right i…

Crawling is an inconvenience, sure it is problematic, but phishing is much more problematic. You can train a machine to parse that thing right-to-left no problem, to tell users to start middle-to-left and then middle-to-right is too much of a burden.

Agreed. Not so much "a burden" as something that you will never be able to teach a large number of people.

Re: Ask HN: why are domain names reversely ordered?

#19

Post by gabriel-coarna »

bajsejohannes wrote: post #8

(Just to clarify...) I know what you mean, but I don't think your question makes sense without comparing it to something. That something would naturally be the path. www.google.com makes as much sense as com.google.www but www.google.com/root/sub/subsub makes less sense than com.google.www/root/sub/subsub or subsub/sub/root/www.google.com Since the latter has consistent increasing or decreasing of specificity, while…

Actually, com.google.www/root/sub/subsub would make the most sense.

The Commercial domain. The Google host/company. The www service/sub-domain. The path.

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