<p>Does a caching-nameserver usually cache the negative DNS response SERVFAIL? </p>

<p>EDIT:
To clarify the question, I can see the caching nameserver caching negative responses NXDOMAIN, NODATA. But it does not do this for SERVFAIL responses. Is this intentional?</p>

One of the timeout fields in the SOA is a "negative timeout". It is usually set to a short time, such as 30 or 60 seconds. So, yes, but for a shorter time than a "positive" response.