[dns-operations] Ultra DNS responding with NXDOMAIN for "www.uber.com"

[Shreyas Zare]

Hello,

It seems Ultra DNS is responding with NXDOMAIN for "www.uber.com" queries.
Please see the response below:

Query Link: https://dnsclient.net/#edns126.ultradns.com/www.uber.com/A/UDP

> {
>   "Metadata": {
>     "NameServer": "edns126.ultradns.com:53 (204.74.66.126:53)",
>     "Protocol": "Udp",
>     "DatagramSize": "213 bytes",
>     "RoundTripTime": "13.92 ms"
>   },
>   "Identifier": 21863,
>   "IsResponse": true,
>   "OPCODE": "StandardQuery",
>   "AuthoritativeAnswer": true,
>   "Truncation": false,
>   "RecursionDesired": true,
>   "RecursionAvailable": false,
>   "Z": 0,
>   "AuthenticData": false,
>   "CheckingDisabled": false,
>   "RCODE": "NxDomain",
>   "QDCOUNT": 1,
>   "ANCOUNT": 3,
>   "NSCOUNT": 1,
>   "ARCOUNT": 0,
>   "Question": [
>     {
>       "Name": "www.uber.com",
>       "Type": "A",
>       "Class": "IN"
>     }
>   ],
>   "Answer": [
>     {
>       "Name": "www.uber.com",
>       "Type": "CNAME",
>       "Class": "IN",
>       "TTL": "300 (5 mins)",
>       "RDLENGTH": "16 bytes",
>       "RDATA": {
>         "Domain": "frontends-all.uber.com"
>       }
>     },
>     {
>       "Name": "frontends-all.uber.com",
>       "Type": "CNAME",
>       "Class": "IN",
>       "TTL": "300 (5 mins)",
>       "RDLENGTH": "18 bytes",
>       "RDATA": {
>         "Domain": "frontends-cloud.uber.com"
>       }
>     },
>     {
>       "Name": "frontends-cloud.uber.com",
>       "Type": "CNAME",
>       "Class": "IN",
>       "TTL": "300 (5 mins)",
>       "RDLENGTH": "13 bytes",
>       "RDATA": {
>         "Domain": "cn-ecg.cfe.uber.com"
>       }
>     }
>   ],
>   "Authority": [
>     {
>       "Name": "uber.com",
>       "Type": "SOA",
>       "Class": "IN",
>       "TTL": "900 (15 mins)",
>       "RDLENGTH": "58 bytes",
>       "RDATA": {
>         "PrimaryNameServer": "edns126.ultradns.com",
>         "ResponsiblePerson": "serviceproviders.uber.com",
>         "Serial": 2019057840,
>         "Refresh": 3600,
>         "Retry": 180,
>         "Expire": 604800,
>         "Minimum": 900
>       }
>     }
>   ],
>   "Additional": []
> }
>
>
However, querying for "cn-ecg.cfe.uber.com" to the same server responds
with an answer:

Query Link:
https://dnsclient.net/#edns126.ultradns.com/cn-ecg.cfe.uber.com/A/UDP

> {
>   "Metadata": {
>     "NameServer": "edns126.ultradns.com:53 (204.74.66.126:53)",
>     "Protocol": "Udp",
>     "DatagramSize": "186 bytes",
>     "RoundTripTime": "18.89 ms"
>   },
>   "Identifier": 9834,
>   "IsResponse": true,
>   "OPCODE": "StandardQuery",
>   "AuthoritativeAnswer": true,
>   "Truncation": false,
>   "RecursionDesired": true,
>   "RecursionAvailable": false,
>   "Z": 0,
>   "AuthenticData": false,
>   "CheckingDisabled": false,
>   "RCODE": "NoError",
>   "QDCOUNT": 1,
>   "ANCOUNT": 1,
>   "NSCOUNT": 4,
>   "ARCOUNT": 0,
>   "Question": [
>     {
>       "Name": "cn-ecg.cfe.uber.com",
>       "Type": "A",
>       "Class": "IN"
>     }
>   ],
>   "Answer": [
>     {
>       "Name": "cn-ecg.cfe.uber.com",
>       "Type": "A",
>       "Class": "IN",
>       "TTL": "300 (5 mins)",
>       "RDLENGTH": "4 bytes",
>       "RDATA": {
>         "IPAddress": "34.98.127.226"
>       }
>     }
>   ],
>   "Authority": [
>     {
>       "Name": "cfe.uber.com",
>       "Type": "NS",
>       "Class": "IN",
>       "TTL": "86400 (1 day)",
>       "RDLENGTH": "22 bytes",
>       "RDATA": {
>         "NameServer": "edns126.ultradns.org"
>       }
>     },
>     {
>       "Name": "cfe.uber.com",
>       "Type": "NS",
>       "Class": "IN",
>       "TTL": "86400 (1 day)",
>       "RDLENGTH": "19 bytes",
>       "RDATA": {
>         "NameServer": "edns126.ultradns.com"
>       }
>     },
>     {
>       "Name": "cfe.uber.com",
>       "Type": "NS",
>       "Class": "IN",
>       "TTL": "86400 (1 day)",
>       "RDLENGTH": "22 bytes",
>       "RDATA": {
>         "NameServer": "edns126.ultradns.net"
>       }
>     },
>     {
>       "Name": "cfe.uber.com",
>       "Type": "NS",
>       "Class": "IN",
>       "TTL": "86400 (1 day)",
>       "RDLENGTH": "22 bytes",
>       "RDATA": {
>         "NameServer": "edns126.ultradns.biz"
>       }
>     }
>   ],
>   "Additional": []
> }
>
> Regards,
*Shreyas Zare*
Technitium <https://technitium.com>
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