EVB-PIC24 WIZnet, EVB-PIC24 Datasheet - Page 84

• Manufacturer Part Number: EVB-PIC24
• Description: Development Boards & Kits - PIC / DSPIC W3150A+EVAL BOARD BASED ON PIC24
• Manufacturer: WIZnet

Specifications of EVB-PIC24

• Rohs: yes
• Product: Development Kits
• Interface Type: RS-232
• Data Bus Width: 16 bit
• Dimensions: 50 mm x 40 mm

3.2.6.6.
Let‟s take a brief look at the DNS(Domain Name System) before DNS Client setup is introduced.
DNS is a system that transforms Internet Domain Name to Internet IP Address or Internet IP Address to
Internet Domain Name. DNS is composed of Name Server that contains mapping table between IP Address
and Domain Name, and DNS resolver that receives query results by transmitting query to Name Server.
DNS resolver queries IP address or Domain Name to be transformed to local Name Server. Local Name
Server which received the Query searches its DB and answers back to the Resolver. If Resolver cannot find
the information it looks up, Local Name Server sends the received query to Name Server at higher layer and
the received answer can be sent to the Resolver.
As seen in <Fig 3.33>, DNS Query and DNS Answer Message transmittable between DNS Resolver and
Name Server are composed of 5 Sections in <Fig 3.34>.
u_char socket(SOCKET s,
flag)
u_int
u_char * buf, u_int len, u_char * addr,
u_int port)
u_int recvfrom(SOCKET s, u_char *
buf,
u_int len, u_char * addr, u_int * port)
void close(SOCKET s)
u_char protocol, u_int port, u_char
DNS Client
RESOLVER
sendto(SOCKET
(CLIENT)
<Fig 3.33: Domain Name System Structure & DNS Message Flow>
© Copyright 2006 WIZnet Co., Inc. All rights reserved.
s,
const
Answer
Query
Creates sockets as TCP/UDP/IP
Transmits data through specific port
of specific Destination
Receives data through any port of
any destination.
Closes the Socket
Name Server
53 Port
Local
Answer
iinChip/socket.c
iinChip/socket.c
iinChip/socket.c
iinChip/socket.c
Query
DB
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