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I am using DNS-crypt proxy as a local DNS server with cloudflare as the resolver.

For some reason I cannot ping www.automaticwebforms.com despite the DNS resolving:

ping

$ ping www.automaticwebforms.com
ping: www.automaticwebforms.com: Name or service not known

netcat

$ netcat www.automaticwebforms.com 80                                                                                                                                                                                    
Error: Couldn't resolve host "www.automaticwebforms.com"

DNS

nslookup -debug www.automaticwebforms.com
Server:         127.0.0.1
Address:        127.0.0.1#53

Non-authoritative answer:
www.automaticwebforms.com       canonical name = automaticwebforms.com.
Name:   automaticwebforms.com
Address: 198.50.128.113

host

host www.automaticwebforms.com
www.automaticwebforms.com is an alias for automaticwebforms.com.
automaticwebforms.com has address 198.50.128.113
automaticwebforms.com mail is handled by 10 mail.automaticwebforms.com.

www.google.com works fine for all of the services above.

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  • It's entirely possible that ICMP traffic is blocked somewhere along the route to that host. Have you tried TCPing or netcat on a known-open port?
    – DopeGhoti
    May 4, 2018 at 22:35
  • @DopeGhoti Can't netcat either: netcat www.automaticwebforms.com 80 Error: Couldn't resolve host "www.automaticwebforms.com" (it's a website so presumably port 80 is open)
    – carloabelli
    May 4, 2018 at 22:37
  • Cloudflare is resolving it now. Transient problem?
    – Rui F Ribeiro
    May 5, 2018 at 3:10
  • @RuiFRibeiro No same issue still.
    – carloabelli
    May 5, 2018 at 3:27
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    The parent and the child disagree on who are the authoritative nameservers for the zone. This creates a whole lot of breakage and there is no incentive to debug it further until this point is resolved. Parent says the nameservers are ns1.exponenciel.com and ns2.exponenciel.com. And these 2 nameservers say the only one authoritative nameserver on the zone is ns.automaticwebforms.com. Since even more it is in-bailiwick and without glue there is no chance this DNS setup will work.
    – Patrick Mevzek
    May 6, 2018 at 23:58

1 Answer 1

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ping(1) checks network connectivity (it sends an ICMP ECHO-REQUEST to the target, and waits for a response; be aware that some totally clueless network "administrators" block ICMP and you won't get answers even if the host is reachable).

DNS (i.e. host(1) or dig(1) results) checks if the nameserver for the hostname is reachable and answers.

They are totally separate, the nameserver will typically run on some different machine, and the RFCs even demand that a copy of the data is kept on at least two servers on different networks. So the host can be down, or otherwise be unreachable, while DNS answers. Or the other way around.

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  • 1
    Thank you for the answer. What is strange to me is that ping cannot even resolve the IP address of the website (which I assume it has to do through DNS) while dig returns the valid IP address fetched through DNS. I would expect that if the host is down that at least it would attempt to ping the IP address but would not receive any ping responses.
    – carloabelli
    May 17, 2018 at 19:51

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