Whats is the difference between AWS ELB and Route53?

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I am new to AWS Route53 and trying to brush up some of the basics. I have a question that might sound silly.

Lets say i have a public load balancer created with its DNS (AWS auto generated). Now i went ahead and got my corporate company to create a CName for the actual ELB A record, so say that CNAME is www.my-website.com.

Now when users start browsing www.my-website.com, their router DNS directly know where this public www.my-website.com is hosted and then once the DNS resolution happens, the request is directly forwarded to my ELB that has that CName to it.

Now all this is good but i would also like to play with Route53 here, so i go ahead and use Route53 to create a hosted zone and add my domain www.my-website.com under it and then create a record set with alias pointing to my actual ELB followed by rest of the configuration.

Now when someone hits www.my-website.com on their browser will the request directly go to the ELB or go to Route53 that will then route it to that ELB?

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amazon-web-servicesamazon-route53amazon-elb
Route53 is nothing more than DNS. An alias in route53 is basically a CNAME, but AWS returns it as an A record. – jordanm
So as per my question, where will the request first go? Will it be directly to the ELB because that is associated with that CNAME www.my-website.com, or will that go to Route53 since its also associated with the ELB using recordset alias? – Ashley
@Ashley the DNS request will go to Route53 to resolve the domain name. The HTTP request will go directly to the load balancer, because DNS servers don't handle HTTP requests. – Mark B

1 Answers

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A summary of what these services provides is below:

  • Route 53 is a DNS Provider provided as a service by AWS. The functionality you're describing using is to store your DNS records within it for resolution.
  • An ELB is an appliance to distribute traffic across multiple nodes.

With your records in Route 53 the below journey takes place:

  • When a client in the browser attempts to go to www.example.com it will first check in its internal cache for any previously stored values for the domain, if theres a value it will be evaluated against a TTL to see if it has been expired.
  • If no value or expired the client will connect to the root domain, then the top level domain continuing until it finds the DNS provider for your domain (. -> .com. -> example.com..
  • Once it finds this DNS provider it will query for your domain, if it matches it will return the resolution value and the TTL.
  • If the value is that of a CNAME (such as an ELB) this process will begin again to resolves the IP address(es) for your hostname. This IP address will be cached by your local client.

If you're using Route 53 and an ELB one advantage would be to use Alias records they actually set your domain record to the IP address which improves the speed of DNS resolution.

So in summary Route 53 is only contacted if the client does not know the resolution value for your domain.