Hi PDNS community,
<br><br>I want implement empty CNAME records instead of empty A records
in our DNS environment. But when I implement the empty records my MX
records won't work anymore.
<br><br>Example:
<br><br><i>nslookup
<br>> set type=mx
<br>> set debug
<br>> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br>Server: 212.54.40.25
<br>Address: 212.54.40.25#53
<br><br>------------
<br> QUESTIONS:
<br> <a href="http://online-engineers.nl">online-engineers.nl</a>, type = MX, class = IN
<br> ANSWERS:
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 20 <a href="http://mx2.global-e.nl">mx2.global-e.nl</a>.
<br> ttl = 120
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 50 <a href="http://mx3.global-e.nl">mx3.global-e.nl</a>.
<br> ttl = 120
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 20 <a href="http://mx1.global-e.nl">mx1.global-e.nl</a>.
<br> ttl = 120
<br> AUTHORITY RECORDS:
<br> ADDITIONAL RECORDS:
<br>------------
<br>Non-authoritative answer:
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 20 <a href="http://mx2.global-e.nl">mx2.global-e.nl</a>.
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 50 <a href="http://mx3.global-e.nl">mx3.global-e.nl</a>.
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 20 <a href="http://mx1.global-e.nl">mx1.global-e.nl</a>.
<br><br>Authoritative answers can be found from:
<br><br></i><br><br>Then I add an empty CNAME: <a href="http://online-engineers.nl">online-engineers.nl</a> CNAME <a href="http://some.otherdomain.nl">some.otherdomain.nl</a>
<br><br>And I start a new nslookup:
<br><i><br>> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br>Server: 212.54.40.25
<br>Address: 212.54.40.25#53
<br><br>------------
<br> QUESTIONS:
<br> <a href="http://online-engineers.nl">online-engineers.nl</a>, type = MX, class = IN
<br> ANSWERS:
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> canonical name = <a href="http://some.otherdomain.nl">some.otherdomain.nl</a>.
<br> ttl = 86400
<br> AUTHORITY RECORDS:
<br> -> nl
<br> origin = <a href="http://ns1.dns.nl">ns1.dns.nl</a>
<br> mail addr = <a href="http://hostmaster.domain-registry.nl">hostmaster.domain-registry.nl</a>
<br> serial = 2012050309
<br> refresh = 7200
<br> retry = 900
<br> expire = 2419200
<br> minimum = 900
<br> ttl = 900
<br> ADDITIONAL RECORDS:
<br>------------
<br>** server can't find <a href="http://online-engineers.nl">online-engineers.nl</a>: NXDOMAIN
<br>Server: 212.54.40.25
<br>Address: 212.54.40.25#53
<br><br>------------
<br> QUESTIONS:
<br> <a href="http://online-engineers.nl">online-engineers.nl</a>, type = MX, class = IN
<br> ANSWERS:
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> canonical name = <a href="http://some.otherdomain.nl">some.otherdomain.nl</a>.
<br> ttl = 86400
<br> AUTHORITY RECORDS:
<br> -> nl
<br> origin = <a href="http://ns1.dns.nl">ns1.dns.nl</a>
<br> mail addr = <a href="http://hostmaster.domain-registry.nl">hostmaster.domain-registry.nl</a>
<br> serial = 2012050309
<br> refresh = 7200
<br> retry = 900
<br> expire = 2419200
<br> minimum = 900
<br> ttl = 900
<br> ADDITIONAL RECORDS:
<br>------------
<br>** server can't find <a href="http://online-engineers.nl">online-engineers.nl</a>: NXDOMAIN
<br>>
<br>>
<br>> </i><br><br>And when I remove the empty CNAME everything works fine again:
<br><i><br>> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br>Server: 212.54.40.25
<br>Address: 212.54.40.25#53
<br><br>------------
<br> QUESTIONS:
<br> <a href="http://online-engineers.nl">online-engineers.nl</a>, type = MX, class = IN
<br> ANSWERS:
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 50 <a href="http://mx3.global-e.nl">mx3.global-e.nl</a>.
<br> ttl = 120
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 20 <a href="http://mx1.global-e.nl">mx1.global-e.nl</a>.
<br> ttl = 120
<br> -> <a href="http://online-engineers.nl">online-engineers.nl</a>
<br> mail exchanger = 20 <a href="http://mx2.global-e.nl">mx2.global-e.nl</a>.
<br> ttl = 120
<br> AUTHORITY RECORDS:
<br> ADDITIONAL RECORDS:
<br>------------
<br>Non-authoritative answer:
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 50 <a href="http://mx3.global-e.nl">mx3.global-e.nl</a>.
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 20 <a href="http://mx1.global-e.nl">mx1.global-e.nl</a>.
<br><a href="http://online-engineers.nl">online-engineers.nl</a> mail exchanger = 20 <a href="http://mx2.global-e.nl">mx2.global-e.nl</a>.
<br><br>Authoritative answers can be found from:
<br></i><br><br>Is there a way to fix this? In the past I found an
article (RFC, sorry I can't find the source anymore) that officially
empty CNAME's isn't allowed in DNS. But many companies works with empty
CNAME's , even google and amazon.
<br><br>So I think there must be a way - or workaround - to fix this.
<br><br>I hope someone can give me a solution.
<br><br>Regards,
<br>Thomas