OpenDNS resolvers (such as resolver1.opendns.com) will resolve myip.opendns.com to your actual IP address. Whether you get A or AAAA records depends on your connection. Since the IP addresses for these resolvers tend to be anycast IPs, I also want to believe they are marginally faster than pinging some central HTTP service that can go down at any time. (Of course, OpenDNS can vanish at any time, too, but I find the risk of that more tolerable than the countless "what is my IP address?" HTTP services out there)

Anyway, I remember hearing before that DNS originally was intended to be used with a broader scope of data than just domain names (hence the existence of TXT records and the like). This website greatly demonstrates how much utility you can get out of DNS.

    dig @ns1-1.akamaitech.net ANY whoami.akamai.net +short


    dig @ns1.google.com TXT o-o.myaddr.l.google.com +short

    nslookup whoami.akamai.net ns1-1.akamaitech.net

Worth noting that Cloudflare run one though, and that seems more likely to be reliable:

https://icanhazip.com/

https://ipv4.icanhazip.com/

https://ipv6.icanhazip.com/

- [1] https://jvns.ca/

- [2] https://dns-lookup.jvns.ca/

- [3] https://messwithdns.net/

DNS Toys - https://news.ycombinator.com/item?id=31704789 - June 2022 (104 comments)

DNS Toys: Useful utilities and services over DNS - https://news.ycombinator.com/item?id=31637226 - June 2022 (1 comment)

https://youtu.be/ANmFZ8rbmnc?si=ndEWH4xY2oxJuEnB

dig A0.0,0.0/0.0,90.0.aerial @dns.toys

and

dig A0.0,0.0/90.0,0.0.aerial @dns.toys

both produce TXT "aerial distance = 10007.06 KM"

The equatorial circumference is 40,075.017 km (24,901.461 mi), while the polar circumference is 40,007.863 km (24,859.734 mi).

I guess there's no great harm in assuming the earth is hypothetically cow shaped, and it avoids that awkward series for shortest distance twixt points following an ellipsoids surface.

https://www.num.uk/

Though going by their roadmap, it may be they're no longer maintaining the service.

The IN (internet) class is the evolutionary "towering cedar" of the moment, but there were the CH (chaos) and HS (hesiod) classes during the cambrian period; you might review those project's purposes and goals.

Arguably the abuse today is in the form of things like ten millisecond windows for retransmission and qname minimization which optimize specifically for cloud-based web services ("happy eyeballs") at the expense of all else (and seemingly without awareness of e.g. buffer bloat). There's a whole world outside of A / AAAA resolution.

It's not unheard of to see two people with pocket protectors having a knife fight (or at least poking at each other with pencils) in the hallway at an Internet confab. "RFC" stands for "Request For Comments" and BCPs (Best Current Practice) are routinely ignored.

https://dnscheck.tools/

https://myip.addr.tools/help

    dig 100USD-INR.fx @dns.toys

The DNS protocol, defined in some RFC, says that I have to make a request a certain way, and that the server has to respond a certain way. One of these ways is that for top level domains that don't exist (for ex. .time is not a currently existing tld), the server is supposed to reply nxdomain, but in reality there is no technical measure stopping it from replying with anything it wants, such as the current time.

In fact, generally speaking, the expectation that the server operators will not fuck you over is the only thing preventing public (and indeed private) DNS operators from returning you bogus data. This is mitigated somewhat by HTTPS, but DNS records themselves are infinitely fakeable with no recourse.

It is possible for an apex domain to contain/be a CNAME, and it simply is done, by many companies: https://serverfault.com/questions/55528/set-root-domain-reco...

A IP = ...1

AAAA IP = ...2

Where 'a' is the type of record. But there are other types of records:

TXT gender = 'male'

So there's a few assumptions here about DNS that are normally true:

1. People are using DNS as a switch board to other services.

2. The values in the switchboard are normally static.

With this setup they're doing something completely different because they're serving back changing values based on the domain. To do this you would need to write a custom DNS server (though the DNS protocol is quite simple.) The reasons this is a clever hack though are as follows:

1. DNS is one of the most widely used and supported protocols. All mainstream programming libraries support it. This includes numerous command-line tools already in operating system. By providing this as a service over DNS it provides an elegant way for command-line tools and libraries to access services with minimal dependencies.

2. It challenges the way the DNS system should be used by tipping the normal assumptions behind its use on its head (direct usage for information, dynamic content for values.) This makes it possible to use DNS directly as an application service rather than as a switch board operator for regular internet services.

3. DNS is so integral that a complex integration wouldn't be needed to add it to existing software. A DNS request is arguably more straight-forwards than a typical web API. Chances are this also has benefits for censorship resistance, too.

All in all a clever hack.

NextDNS gives you a name that you can put in certain UIs (like "Private DNS" in Android) -- I always assumed there was just something special about those.

[1]: https://www.theregister.com/2023/05/16/alpine_linux_318/

dns.toys runs a (custom) DNS resolver. The example dig commands are asking this resolver. They are not using your configured (public) resolver. The custom resolver can return whatever it wants depending on the request. You could also ask the resolver what the IP (A-record) of e.g. "google.com" is and it could answer with whatever it wants.

Therefore, they actually just use one domain: dns.toys.

  dig +short TXT mumbai.weather @dns.google
  # NXDOMAIN
 
  dig +short TXT mumbai.weather @dns.toys  
  "Mumbai (IN)" "30.90C (87.62F)" "45.90% hu." "clearsky_day" "15:30, Sun"
  "Mumbai (IN)" "28.10C (82.58F)" "56.00% hu." "fair_day" "17:30, Sun"
  ...

https://dns.lookup.dog/

Surely Windows has some kind of DNS lookup tool!

   Resolve-DnsName

The README for this project may explain some of the general benefits (my project): https://github.com/m3047/rkvdns

HTTP is everywhere. I think SOAP sucks, but it's everywhere and it works well enough. (For that matter XHR sucks, but even I use it occasionally.)

(This is not the first time DNS Toys has shown up on Hacker News, there's a link in another comment.)