dns-search determines which domain is appended for dns lookups.
Normally you will specify here the same domain as returned by
For detailed information see the following quote from
search Search list for host-name lookup.
The search list is normally determined from the local domain name; by default, it contains only the local domain
name. This may be changed by listing the desired domain search path following the search keyword with spaces or tabs
separating the names. Resolver queries having fewer than ndots dots (default is 1) in them will be attempted using
each component of the search path in turn until a match is found. For environments with multiple subdomains please
read options ndots:n below to avoid man-in-the-middle attacks and unnecessary traffic for the root-dns-servers. Note
that this process may be slow and will generate a lot of network traffic if the servers for the listed domains are
not local, and that queries will time out if no server is available for one of the domains.
The search list is currently limited to six domains with a total of 256 characters.