After testing your domain and re-reading your question, I realized that this is likely the problem:
Created Hosted Zone with new A record with Name: mydomain.com Alias :
no Value :
Since you're just using an individual EC2 instance you don't want to be using an alias. As the Route53 documentation states, aliases only apply to Elastic Load Balancers, S3 buckets, CloudFront (CDN) endpoints, and records within the same domain.
What you likely want to do is remove any A records that you have defined and then create a CNAME for mydomain.com (not an alias) that has a value of the EC2 DNS record for your instance. You might also want to create a www.mydomain.com record that is also a CNAME to your EC2 DNS record.
Once you've created those CNAME records then nslookup should give you results something like this:
$ nslookup mydomain.com
Server: 10.1.2.11
Address: 10.1.2.11#53
Non-authoritative answer:
mydomain.com canonical name = ec2-111-222-123-1.eu-west-1.compute.amazonaws.com.
Name: ec2-111-222-123-1.eu-west-1.compute.amazonaws.com
Address: 111.222.123.1
Don't forget that when you make changes to your DNS records it will take some time for those changes to take effect when you test it. Route53 defaults to a TTL of 300 seconds (5 minutes) so unless you changed the TTL you should see the change reflected within 5 minutes. You can see how many seconds are left in the TTL if you use dig instead of nslookup:
$ dig www.news.com
...
;; ANSWER SECTION:
www.news.com. 234 IN CNAME phx1-rb-gtm3-tron-xw-lb.cnet.com.
The "234" there means that the local DNS server will expire this result in 234 seconds and query the authoritative DNS server once again. You'll need to wait for that value to hit 0 before your local DNS server will look up mydomain.com or www.mydomain.com the next time around.
Edit:
I would suggest double-checking your nameservers in Route53 and verify them in your domain registration. If I do a whois on your domain it shows:
$ whois trueweekends.in
...
Name Server:NS-1089.AWSDNS-08.ORG
Name Server:NS-765.AWSDNS-31.NET
Name Server:NS-431.AWSDNS-53.COM
Name Server:NS-1886.AWSDNS-43.CO.UK
I should be able to query any of those nameservers and get a listing of the same nameservers back from them. For example, take a look at the domain todoist.com, which is also hosted on AWS:
$ whois todoist.com
...
Name Server: NS-938.AWSDNS-53.NET
Name Server: NS-1046.AWSDNS-02.ORG
Name Server: NS-1799.AWSDNS-32.CO.UK
Name Server: NS-158.AWSDNS-19.COM
If I query one of those nameservers for a list of nameservers associated with todoist.com then I get:
$ dig @NS-938.AWSDNS-53.NET todoist.com NS
...
;; ANSWER SECTION:
todoist.com. 172800 IN NS ns-1046.awsdns-02.org.
todoist.com. 172800 IN NS ns-158.awsdns-19.com.
todoist.com. 172800 IN NS ns-1799.awsdns-32.co.uk.
todoist.com. 172800 IN NS ns-938.awsdns-53.net.
If I do the same sort of thing with your domain I don't get any results. The following queries all result in no answers:
$ dig @NS-1089.AWSDNS-08.ORG trueweekends.in NS
$ dig @NS-765.AWSDNS-31.NET trueweekends.in NS
$ dig @NS-1799.AWSDNS-32.CO.UK trueweekends.in NS
$ dig @NS-158.AWSDNS-19.COM trueweekends.in NS
If you're 100% sure that you have the correct nameservers listed in your domain (the ones I mention above match what Route53 shows you should be using) and you're sure your records within Route53 are set up properly then I would suggest contacting AWS support because it sounds like there's some sort of issue with Route53 not handling your domain properly.
