Need to optimize EDNS0 Client Subnet (ECS) with some large CDN services

Hi,

After using nextdns for a while with the ultralow server, I realized that the team should further optimize ECS with large CDN services.

For Akamai's CDN service, I found nextdns doesn't send ECS when querying for domains with Akamai's CNAME.

Some big companies like Apple, Let's Encrypt,... use Akamai CDN to deliver data, but nextdns ECS doesn't send ECS. Meanwhile, Wikipedia's domain name when resolving to the same IP (without using a 3rd party CDN service), nextdns sends ECS.

Should nextdns consider to improve ECS, for example sending ECS when the domain name has the CNAME of the CDN.

For example:

Client: nextdns-cli

Country: Vietnam

ISP: Viettel

* Domain `www.apple.com`

- With nextdns

odroid@odroid:~$ dig www.apple.com CHAOS
;; Warning: Message parser reports malformed message packet.

; <<>> DiG 9.16.1-Ubuntu <<>> www.apple.com CHAOS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35036
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 7
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;www.apple.com.            CH    A

;; ANSWER SECTION:
www.apple.com.        5    IN    CNAME    www.apple.com.edgekey.net.
www.apple.com.edgekey.net. 5    IN    CNAME    www.apple.com.edgekey.net.globalredir.akadns.net.
www.apple.com.edgekey.net.globalredir.akadns.net. 5 IN CNAME e6858.dscx.akamaiedge.net.
e6858.dscx.akamaiedge.net. 5    IN    A    23.56.21.204
;; ADDITIONAL SECTION:
proto.nextdns.io.    0    CH    TXT    "DOH"
server.nextdns.io.    0    CH    TXT    "greencloud-han-1"
profile.nextdns.io.    0    CH    TXT    "fp9bcd6aeabd69c3f1"
client.nextdns.io.    0    CH    TXT    "171.245.214.***"
client-name.nextdns.io.    0    CH    TXT    "nextdns-cli"
smart-ecs.nextdns.io.    0    CH    TXT    "not sent"
;; Query time: 80 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 09 10:58:34 +07 2022
;; MSG SIZE  rcvd: 401

- With Google DNS

odroid@odroid:~$ dig www.apple.com @8.8.8.8
; <<>> DiG 9.16.1-Ubuntu <<>> www.apple.com @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12759
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;www.apple.com.            IN    A
;; ANSWER SECTION:
www.apple.com.        1783    IN    CNAME    www.apple.com.edgekey.net.
www.apple.com.edgekey.net. 21560 IN    CNAME    www.apple.com.edgekey.net.globalredir.akadns.net.
www.apple.com.edgekey.net.globalredir.akadns.net. 3516 IN CNAME    e6858.dscx.akamaiedge.net.
e6858.dscx.akamaiedge.net. 15    IN    A    104.93.16.212
;; Query time: 32 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Sep 09 11:00:25 +07 2022
;; MSG SIZE  rcvd: 192

- With DNS ISP Viettel

odroid@odroid:~$ dig www.apple.com @203.113.188.1
; <<>> DiG 9.16.1-Ubuntu <<>> www.apple.com @203.113.188.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46103
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: d61f648323b836c801000000631abaafcb58044b25c10b52 (good)
;; QUESTION SECTION:
;www.apple.com.            IN    A
;; ANSWER SECTION:
www.apple.com.        100    IN    CNAME    www.apple.com.edgekey.net.
www.apple.com.edgekey.net. 17955 IN    CNAME    www.apple.com.edgekey.net.globalredir.akadns.net.
www.apple.com.edgekey.net.globalredir.akadns.net. 901 IN CNAME e6858.dscx.akamaiedge.net.
e6858.dscx.akamaiedge.net. 80    IN    A    171.236.60.223
;; Query time: 4 msec
;; SERVER: 203.113.188.1#53(203.113.188.1)
;; WHEN: Fri Sep 09 11:01:51 +07 2022
;; MSG SIZE  rcvd: 226

{ "ipAddress": "171.236.60.223", "continentCode": "AS", "continentName": "Asia", "countryCode": "VN", "countryName": "Vietnam", "isEuMember": false, "currencyCode": "VND", "currencyName": "Dong", "phonePrefix": "84", "languages": [ "vi", "en", "fr", "zh", "km" ], "stateProvCode": "HN", "stateProv": "Hanoi", "district": "Hoan Kiem", "city": "Hanoi", "geonameId": 1581130, "latitude": 21.0278, "longitude": 105.834, "gmtOffset": 7, "timeZone": "Asia/Bangkok", "weatherCode": "VMXX0006", "asNumber": 7552, "asName": "VIETEL-AS-AP", "isp": "Viettel Corporation", "linkType": "dsl", "usageType": "consumer", "organization": "Vietel", "isCrawler": false, "isProxy": false, "threatLevel": "low" }

* Domain `e1.o.lencr.org`

odroid@odroid:~$ dig e1.o.lencr.org CHAOS
;; Warning: Message parser reports malformed message packet.
; <<>> DiG 9.16.1-Ubuntu <<>> e1.o.lencr.org CHAOS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13569
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 7
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;e1.o.lencr.org.            CH    A
;; ANSWER SECTION:
e1.o.lencr.org.        5    IN    CNAME    o.lencr.edgesuite.net.
o.lencr.edgesuite.net.    5    IN    CNAME    a1887.dscq.akamai.net.
a1887.dscq.akamai.net.    5    IN    A    23.74.15.72
a1887.dscq.akamai.net.    5    IN    A    23.74.15.131
;; ADDITIONAL SECTION:
proto.nextdns.io.    0    CH    TXT    "DOH"
server.nextdns.io.    0    CH    TXT    "greencloud-han-1"
profile.nextdns.io.    0    CH    TXT    "fp9bcd6aeabd69c3f1"
client.nextdns.io.    0    CH    TXT    "171.245.214.***"
client-name.nextdns.io.    0    CH    TXT    "nextdns-cli"
smart-ecs.nextdns.io.    0    CH    TXT    "not sent"
;; Query time: 80 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 09 11:10:36 +07 2022
;; MSG SIZE  rcvd: 351

- With Google DNS

odroid@odroid:~$ dig e1.o.lencr.org @8.8.8.8
; <<>> DiG 9.16.1-Ubuntu <<>> e1.o.lencr.org @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19241
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;e1.o.lencr.org.            IN    A
;; ANSWER SECTION:
e1.o.lencr.org.        120    IN    CNAME    o.lencr.edgesuite.net.
o.lencr.edgesuite.net.    1700    IN    CNAME    a1887.dscq.akamai.net.
a1887.dscq.akamai.net.    20    IN    A    125.234.51.9
a1887.dscq.akamai.net.    20    IN    A    125.234.51.8
;; Query time: 52 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Sep 09 11:11:55 +07 2022
;; MSG SIZE  rcvd: 142

- With DNS ISP Viettel

odroid@odroid:~$ dig e1.o.lencr.org @203.113.188.1
; <<>> DiG 9.16.1-Ubuntu <<>> e1.o.lencr.org @203.113.188.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24517
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: e7da11ad4928b44c01000000631abd53880bfc89cfcd4936 (good)
;; QUESTION SECTION:
;e1.o.lencr.org.            IN    A
;; ANSWER SECTION:
e1.o.lencr.org.        97    IN    CNAME    o.lencr.edgesuite.net.
o.lencr.edgesuite.net.    19789    IN    CNAME    a1887.dscq.akamai.net.
a1887.dscq.akamai.net.    25    IN    A    125.234.51.9
a1887.dscq.akamai.net.    25    IN    A    125.234.51.19
;; Query time: 4 msec
;; SERVER: 203.113.188.1#53(203.113.188.1)
;; WHEN: Fri Sep 09 11:13:07 +07 2022
;; MSG SIZE  rcvd: 173

{ "ipAddress": "125.234.51.9", "continentCode": "AS", "continentName": "Asia", "countryCode": "VN", "countryName": "Vietnam", "isEuMember": false, "currencyCode": "VND", "currencyName": "Dong", "phonePrefix": "84", "languages": [ "vi", "en", "fr", "zh", "km" ], "stateProvCode": "HN", "stateProv": "Hanoi", "district": "Hoan Kiem", "city": "Hanoi", "geonameId": 1581130, "latitude": 21.0278, "longitude": 105.834, "gmtOffset": 7, "timeZone": "Asia/Bangkok", "weatherCode": "VMXX0006", "asNumber": 7552, "asName": "VIETEL-AS-AP", "isp": "Viettel Corporation", "linkType": "dsl", "usageType": "consumer", "organization": "xDSL Services", "isCrawler": false, "isProxy": false, "threatLevel": "low" }

* Domain `vi.wikipedia.org`

odroid@odroid:~$ dig vi.wikipedia.org CHAOS
;; Warning: Message parser reports malformed message packet.
; <<>> DiG 9.16.1-Ubuntu <<>> vi.wikipedia.org CHAOS
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28900
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 7
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;vi.wikipedia.org.        CH    A
;; ANSWER SECTION:
vi.wikipedia.org.    5    IN    CNAME    dyna.wikimedia.org.
dyna.wikimedia.org.    5    IN    A    103.102.166.224
;; ADDITIONAL SECTION:
server.nextdns.io.    0    CH    TXT    "greencloud-han-1"
profile.nextdns.io.    0    CH    TXT    "fp9bcd6aeabd69c3f1"
proto.nextdns.io.    0    CH    TXT    "DOH"
client.nextdns.io.    0    CH    TXT    "171.245.214.***"
client-name.nextdns.io.    0    CH    TXT    "nextdns-cli"
smart-ecs.nextdns.io.    0    CH    TXT    "23.40.76.0/24"
;; Query time: 536 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Sep 09 11:58:23 +07 2022
;; MSG SIZE  rcvd: 304

- With Google DNS

odroid@odroid:~$ dig vi.wikipedia.org @8.8.8.8
; <<>> DiG 9.16.1-Ubuntu <<>> vi.wikipedia.org @8.8.8.8
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24082
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;vi.wikipedia.org.        IN    A
;; ANSWER SECTION:
vi.wikipedia.org.    19800    IN    CNAME    dyna.wikimedia.org.
dyna.wikimedia.org.    501    IN    A    103.102.166.224
;; Query time: 36 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Fri Sep 09 11:58:33 +07 2022
;; MSG SIZE  rcvd: 90

- With ISP DNS Viettel

odroid@odroid:~$ dig vi.wikipedia.org @203.113.188.1
; <<>> DiG 9.16.1-Ubuntu <<>> vi.wikipedia.org @203.113.188.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32811
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; COOKIE: 37b024624b5417f401000000631ac801ff05c8d436530fa0 (good)
;; QUESTION SECTION:
;vi.wikipedia.org.        IN    A
;; ANSWER SECTION:
vi.wikipedia.org.    39727    IN    CNAME    dyna.wikimedia.org.
dyna.wikimedia.org.    309    IN    A    103.102.166.224
;; Query time: 4 msec
;; SERVER: 203.113.188.1#53(203.113.188.1)
;; WHEN: Fri Sep 09 11:58:41 +07 2022
;; MSG SIZE  rcvd: 121