Charter DNS servers returning invalid IP addresses

Wed Oct 25 23:37:37 UTC 2023

Dear NANOG-er,

Hope this email finds you in good health!

Please see my comments below, inline...

Thanks,

Le 25/10/2023 à 18:50, Jason J. Gullickson via NANOG a écrit :
>
> I've been working for a week or so to solve a problem with DNS 
> resolution for Charter customers for our domain bonesinjars.com.  I've 
> reached-out to Charter directly but since I'm not a customer I 
> couldn't get any help from them.  I was directed by a friend to this 
> list in hopes that there may be able to reach a Charter/Spectrum 
> engineer who might be able to explain and/or resolve this one.
>
> A dig against Google's DNS servers correctly returns 4 A records:
>
>
> dig bonesinjars.com 8.8.8.8
>

...instead of the above, you could try the following command:

`dig bonesinjars.com. @9.9.9.9 +nsid +edns=0 +all +short`

Please, do note the sign `@` and the trailing dot `.`

>
> [...]
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 26879
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
>
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 65494
> ;; QUESTION SECTION:
> ;8.8.8.8.                       IN      A
>

...this is unexpected! given what you said.

>
> ;; Query time: 35 msec
> ;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP)
> ;; WHEN: Mon Oct 23 10:26:32 CDT 2023
> ;; MSG SIZE  rcvd: 36
>
>
> Verizon, AT&T, Comcast and all other DNS servers we tested return the 
> same 4 A records.  However the same dig against a Charter DNS 
> (24.196.64.53) returns only 127.0.0.54:
>
>
> dig bonesinjars.com 24.196.64.53
>
>

`dig cmnog.cm. @24.196.64.53 +nsid +edns=0 +all`

or

dig cmnog.cm. @`dig -x 24.196.64.53 +short` +nsid +edns=0 +all

> ; <<>> DiG 9.16.1-Ubuntu <<>> bonesinjars.com 24.196.64.53
> [...]
> ;; QUESTION SECTION:
> ;bonesinjars.com.        IN    A
>
> ;; ANSWER SECTION:
> bonesinjars.com.    60    IN    A    127.0.0.54
>
> [...]
>
> ;; QUESTION SECTION:
> ;24.196.64.53.            IN    A
>
>

...it's not what you wanted to test!
`dig` understood it otherwise.

...associating the @ sign with the above IPv4 address
would have corrected the behavior of `dig`:
*@24.196.64.53*

>
> ;; ANSWER SECTION:
> 24.196.64.53.        86400    IN    A    24.196.64.53
>
> ;; Query time: 27 msec
> ;; SERVER: 127.0.0.53#53(127.0.0.53)
> [...]
>
>
> Any help understanding and addressing this is greatly appreciated!
>
>
>

Hi Jason,

Thanks for your email, brother.

...you should note that:

n#1. each of the command you shared above is not
producing the expected behavior. Please replace
it by the one i suggested, and observe the diff.

n#2. the DNS resolver you try to use appears to not
being, actually, available for any request.
Just try: `dig @24.196.64.53 cm.` or even:
`dig @24.196.64.53 ns1.charter.com.`

Maybe you should, first clarify what you needed to
achieve.

That said! maybe it's a simple matter of changing
a DNS resolver? have you ask to someone within
Charter's network to try with quad9, for example?
...or any other public DNS resolver, to be fair.

Hope this helps!

Shalom,
--sb.

>
> Jason
>

-- 
Best Regards !

baya.sylvain [AT cmNOG DOT cm]
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