What is the path leading a "DNS query" to GetHostByName()

[valere]

As a newcomer in Dns I would need some explanations to make and send a
DNS Srv query. My goal is to get the IP_address of a Http server
furnished by/in the RR (from the DNS server).


The way one builds a simple DNS query is very transparent (to me).
Meaning I use 'gethostbyname' standard API:


struct	hostent	*	remoteHost;

	myHost = gethostbyname("OneGivenKnownHttpDomainName"); 
	IP_Http_Server = myHost->h_addr; 	
        // Here my goal is reached: IP_Http_Server has been identified


I "guess" that the standard DNS query has been (automatically) built
by "gethostbyname" like this:

QUERY:	 	
[QNAME="OneGivenKnownHttpDomainName", QCLASS=IN" ...]

and transmitted (how ? Via socket mechanism ?...) to the targeted DNS
server. Am I wrong ? I see no clear binding between my supposed
previous "DNS query" form and "gethostbyname" action.


Things are getting much more mysterious when intending to proceed with
a DNS Srv query. I would like to build and send a DNS Srv query this
way:

QUERY:
[QNAME="SpecificService._tcp_.OneGivenDomainName", QCLASS="IN",
QTYPE="SRV"]

But how to transmit such a query to the targeted DNS server ? Still
Using  "gethostbyname" ? Or Is there another API that would be
dedicated to that new kind of specific DNS query ? Which one ? Sorry
for so much naivety.