(Added in the section for CURLOPT_DNS_CACHE_TIMEOUT, pointed out on the

curl-library list on July 9th 2008 by Mathew Hounsell)

NOTE: the name resolve functions of various libc implementations don't re-read
name server information unless explicitly told so (by for example calling
Ires_init(3). This may cause libcurl to keep using the older server even
if DHCP has updated the server info, and this may look like a DNS cache issue
to the casual libcurl-app user.