Routing traffic to an ELB load balancer giving 404 error - amazon-web-services

Question

I have seen quite a few posts talking almost about the same, but none of those covered my case.
I have 2 accounts, A and B, in which:
In account A I have a hosted zone with the domain, domainA.com and a load balancer.
In account B I have another hosted zone, which is a subdomain, staging.domainA.com and another load balancer.
I would like to redirect from one record in domainA.com hosted zone, product.domainA.com to the ELB load balancer in account B, product.staging.domainA.com.
I have thoroughly followed the steps documented in Routing traffic to an ELB load balancer
. An even, they appear to cover my case, because the doc refers at some point in steps 1 and 6 to have a hosted zone and ELB load balancer in different accounts.
Unfortunately, it's not working. I'm getting a 404 error not found. When using dig command the output is exactly the same:
tomas#DESKTOP-EMM3Q9L:~$ dig product.domainA.com
; <<>> DiG 9.11.3-1ubuntu1.13-Ubuntu <<>> product.domainA.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55731
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;product.domainA.com. IN A
;; ANSWER SECTION:
product.domainA.com. 60 IN A X.X.X.X
;; Query time: 41 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Tue Dec 08 16:30:21 STD 2020
;; MSG SIZE rcvd: 50
====================================================================================================================================
tomas#DESKTOP-EMM3Q9L:~$ dig product.staging.domainA.com
; <<>> DiG 9.11.3-1ubuntu1.13-Ubuntu <<>> product.staging.domainA.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41318
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;product.staging.domainA.com. IN A
;; ANSWER SECTION:
product.staging.domainA.com. 41 IN A X.X.X.X
;; Query time: 15 msec
;; SERVER: 192.168.0.1#53(192.168.0.1)
;; WHEN: Tue Dec 08 16:30:58 STD 2020
;; MSG SIZE rcvd: 58
(Actual domain names have been changed as well as IP, which in this case, X.X.X.X represents the SAME IP address in both dig.
Do you know what may be going on? Let me know if you need further details. Thank you.

Answer 1

This could very much be because of a listener rule in your ALB, that only accepts requests from a particular host / domain name.
Check them, and see whether the 404 error could be due to that. In my case at least, it was about that.
For more see: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/listener-update-rules.html