Why instance hostnames are not case sensitive

[zhangyangyang]

I create some instances in R.I find these instances` hostnames are not sensitive.

eg, The name I input is TEST,but login the instance,the hostname is test.

I study the code of creating instances, but I find a function named sanitized_hostname.
In this function,it will call the function hostname.lower().But I do not know why do like this.

Can somebody help me explain this problem?

[Balazs Gibizer (balazs-gibizer)]

By the RFC952 [1] the hostname is case-insensitive: "No distinction is made between upper and lower case."

By the RCF4343 the DNS lookups are also case insensitives [2]: "According to the original DNS design decision, comparisons on name lookup for DNS queries should be case insensitive"

[1] https://tools.ietf.org/html/rfc952
[2] https://tools.ietf.org/html/rfc4343