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iwein
Asked: 2013-01-04 04:58:34 +0800 CST

How do CNAME and A records interact (in this weird case)

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I've managed to surprise myself with some DNS configuration. This is the actual output of my terminal:

[]$ host www.sepa-converter.nl
www.sepa-converter.nl is an alias for sepa-converter.herokuapp.com.
sepa-converter.herokuapp.com has address 184.73.167.111

[]$ host sepa-converter.herokuapp.com
sepa-converter.herokuapp.com has address 184.72.248.52

The result is that if you browse to www.sepa-converter.nl, you do not get the content served by sepa-converter.herokuapp.com.

I've used sepa-converter.nl as an alias for overopsepa.nl. And I want the mails to keep showing up at my Google Apps account. For that reason I've kept the A and MX records, but just changed the CNAMES to point to another server.

Why doesn't this resolve www.sepa-converter.nl to the right heroku app?

UPDATE: I understand that heroku doesn't return the same IP each time and I understand that that's not a problem. The problem is that the http requests serve content that is coming from a different dyno than the one aliased. If you check www.sepa-converter.nl against sepa-converter.herokuapp.com you'll see a different index.html being served.

domain-name-system

3 Answers

  1. This hostname have more that one IP and it is not an issue. I got different IPs on each dig query made to this hostname:

    sgeorge-mn:~ sgeorge$ dig sepa-converter.herokuapp.com +short
50.19.86.241
sgeorge-mn:~ sgeorge$ dig sepa-converter.herokuapp.com +short
107.20.162.205
sgeorge-mn:~ sgeorge$ dig sepa-converter.herokuapp.com +short
54.243.85.64
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  2. Your DNS is properly configured, however the webserver you are referencing to is not configured to host the domain "www.sepa-converter.nl".

    To make the webserver host "www.sepa-converter.nl" a "ServerAlias" must be configured in the apache configuration.

    Reference ServerAlias in the apache documentation.

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  3. Nothing is wrong with your DNS setup. You need to tell Heroku about the hostname you want to use.

    heroku domains:add www.sepa-converter.nl
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