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Is DNS case sensitive?

Posted on 2008-11-05
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Hi

One of our applications cannot seem to be able to resolve DNS names unless they are in lower case (which they are entered in the DNS system on).

I was always under the impression that DNS wasn't case sensitive.

Could someone clarify?
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Question by:kam_uk
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mrwalker15 earned 600 total points
ID: 22885098
DNS is not case sensitive.

Can you provide more details?
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by:kam_uk
ID: 22885114
The DNS record is

ServerA > 192.168.1.1

The application can resolve ServerA to 192.168.1.1

But not SERVERA to 192.168.1.1

Is this an application problem?
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by:ggoossens
ggoossens earned 400 total points
ID: 22885115
No. DNS on itself is not case sensitive (RFC 4343) but it depends on your application how it interpretes the received info. As stated into RFC 4343:
"However, the individual octets of which DNS names consist are not limited to valid ASCII character codes.  They are 8-bit bytes, and all values are allowed.  Many applications, however, interpret them as ASCII characters."
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by:kam_uk
ID: 22885120
Thanks

"However, the individual octets of which DNS names consist are not limited to valid ASCII character codes.  They are 8-bit bytes, and all values are allowed.  Many applications, however, interpret them as ASCII characters."

- What does this exactly mean? :)
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by:mrwalker15
ID: 22885142
What is the FQDN? You may be using WINS/NETBIOS there instead of DNS.

Can you post an NSLOOKUP output?

Thanks.
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by:ggoossens
ID: 22885232
When your application sends an lookup string, it can translate the answer in lower case (although in DNS it was set into uppercase). Here can the wrong conversion happen...
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