Cannot reach my route 53 private hosted zone from a ec2 instance

Question

i have a question regarding my network and dns setup in the AWS.
I wish to configure Route53 DNS Resolution with a private hosted zone in our Infrastructure Account. The private hosted zone is named "aws.ui.local" and has an entry for a Keycloak running in a VPC in the same account. Our company network is connected with a VPN (and accordingly routed) as well as a set up DNS forwarding to the private hosted zone route 53 dns.
Thus i can successfully access the keycloak with an Type A entry (keycloak-dev.aws.ui.local) from within our company network. So Route 53 works fine from outside the AWS.\

Yet the issue lies within AWS. I cannot reach services in my vpcs. The VPC the keycloak is running in has enabled DNS hostnames and DNS resolution as well as an DHCP options set for the domain-name "aws.ui.local" as DNS "AmazonProvidedDNS". Now if i connect to the ec2 instance where the keycloak is running and try to ping "keycloak-dev.aws.ui.local" i get "ping: keycloak-dev.aws.ui.local: Name or service not known".

A dig returns:

;; global options: +cmd
;; Got answer:
;; WARNING: .local is reserved for Multicast DNS
;; You are currently testing what happens when an mDNS query is leaked to DNS
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 26955
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;keycloak-dev.aws.ui.local. IN A

;; AUTHORITY SECTION:
.                       259     IN      SOA     a.root-servers.net. nstld.verisign-grs.com. 2021061000 1800 900 604800 86400

;; Query time: 0 msec
;; SERVER: 10.79.230.2#53(10.79.230.2)
;; WHEN: Thu Jun 10 08:05:36 UTC 2021
;; MSG SIZE  rcvd: 144

A nslookup returns

nslookup keycloak-dev.aws.ui.local
Server:         10.79.230.2
Address:        10.79.230.2#53

** server can't find keycloak-dev.aws.ui.local: NXDOMAIN

I already tried various trouble shooting pages from aws but nothing helped.

Greetings,

Eric

Answer 1

Well I simply did not attach the VPCs to the Hosted Zone.