ECS being disregarded sometimes for Akamai domains

[Agneev Mukherjee]

Hello,

I have dnsmasq configured with a ECS subnet and I can verify that the data actually goes through.

```

~> kdig TXT o-o.myaddr.l.google.com +short @xxx
"74.125.178.133"
"edns0-client-subnet 150.107.179.0/24"

```

However, sometimes it returns IPs outside of ISP's Akamai cache:

```sh

# ECS miss

~> kdig @xxx iosapps.itunes.apple.com
;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 43252
;; Flags: qr rd ra; QUERY: 1; ANSWER: 7; AUTHORITY: 0; ADDITIONAL: 0

;; QUESTION SECTION:
;; iosapps.itunes.apple.com.                IN        A

;; ANSWER SECTION:
iosapps.itunes.apple.com.        18        IN        CNAME        iosapps.itunes-apple.com.akadns.net.
iosapps.itunes-apple.com.akadns.net. 21        IN        CNAME        iosapps.itunes.g.aaplimg.com.
iosapps.itunes.g.aaplimg.com.        3        IN        CNAME        iosapps-in-lb.itunes-apple.com.akadns.net.
iosapps-in-lb.itunes-apple.com.akadns.net. 270        IN        CNAME        iosapps.itunes.apple.com.edgesuite.net.
iosapps.itunes.apple.com.edgesuite.net. 21584        IN        CNAME        a1212.dscda1.akamai.net.
a1212.dscda1.akamai.net.        11        IN        A        23.198.4.56
a1212.dscda1.akamai.net.        11        IN        A        23.198.4.51

;; Received 273 B
;; Time 2022-01-22 21:19:43 IST
;; From xxx@xxx in 40.8 ms

```

```sh

# ECS hit

~> kdig @xxx iosapps.itunes.apple.com
;; ->>HEADER<<- opcode: QUERY; status: NOERROR; id: 58316
;; Flags: qr rd ra; QUERY: 1; ANSWER: 7; AUTHORITY: 0; ADDITIONAL: 0

;; QUESTION SECTION:
;; iosapps.itunes.apple.com.                IN        A

;; ANSWER SECTION:
iosapps.itunes.apple.com.        279        IN        CNAME        iosapps.itunes-apple.com.akadns.net.
iosapps.itunes-apple.com.akadns.net. 268        IN        CNAME        iosapps.itunes.g.aaplimg.com.
iosapps.itunes.g.aaplimg.com.        1        IN        CNAME        iosapps-in-lb.itunes-apple.com.akadns.net.
iosapps-in-lb.itunes-apple.com.akadns.net. 123        IN        CNAME        iosapps.itunes.apple.com.edgesuite.net.
iosapps.itunes.apple.com.edgesuite.net. 20786        IN        CNAME        a1212.dscda1.akamai.net.
a1212.dscda1.akamai.net.        9        IN        A        203.171.247.234
a1212.dscda1.akamai.net.        9        IN        A        203.171.247.225

;; Received 273 B
;; Time 2022-01-22 21:19:45 IST
;; From xxx@xxx in 44.4 ms

```

[pun...@google.com]

Can you file a ticket using https://b.corp.google.com/issues/new?component=191885&template=1213505?

Provide as much relevant detail as possible including where (metro) you are seeing the problem.