|
||
| Products Download Events Support Videos | ||
Technical Support
On-Line Manuals
RL-ARM User's Guide (MDK v4)
RL-RTX
RL-FlashFS
RL-TCPnet
TCP Socket
Opening TCP Connection
TCP Active Open
TCP Passive Open
Sending TCP Data
Example for Sending Data
Multiple TCP Connections
UDP Socket
Opening UDP Connection
Sending UDP Data
When DHCP Enabled
When ARP Cache Empty
Example for Sending Data
IP Multicasting
Multiple UDP Connections
Configuring RL-TCPnet
Static Configuration
System Definitions
Ethernet Network Interface
PPP Network Interface
SLIP Network Interface
UDP Socket
TCP Socket
BSD Socket
HTTP Server
Telnet Server
TFTP Server
TFTP Client
FTP Server
FTP Client
DNS Client
SMTP Client
SNMP Agent
SNTP Client
Error Function
Runtime Configuration
Library Files
Using RL-TCPnet
Stand Alone
With RTX Kernel
Event Driven Operation
IP Address Assignment
Ethernet Interface
PPP Interface
SLIP Interface
Localhost
Applications
HTTP Server
Script Language
CGI Functions
Ajax Support
Using XML
XML Example
How it works
SOAP Support
SOAP Interface
Large POST Messages
Web Pages
Default Page
Error Pages
Web on SD Card
Web Update
File System Interface
Http Caching
How it works
Internal Web
External Web
Multi-user Authentication
Using RAM File System
FCARM File Converter
PRINT Directive
NOPRINT Directive
PAGEWIDTH Directive
PAGELENGTH Directive
ROOT Directive
Telnet Server
Command Line Interface
Multi-user Authentication
Sending Reply Message
Short Reply
Long Reply
Continuous Screen Update
TFTP Server
File System Interface
TFTP Client
File System Interface
FTP Server
File System Interface
Multi-user Authentication
Supported Commands
FTP Client
File System Interface
SMTP Client
SNMP Agent
MIB Database
MIB Interface
MIB Entry
MIB Table
DNS Resolver
Starting DNS
Device Drivers
Ethernet Driver
Interrupt Mode
Modem Driver
Serial Driver
Using Serial Link
Cable Connection
Modem Connection
Windows Dial-up
Add Direct Serial Link
New Dial-up Connection
Configure PPP Dial-up
Configure SLIP Dial-up
Debugging
Enabling Debug
Debug Level
Redirecting Output
Function Overview
BSD Routines
CGI Routines
Ethernet Routines
FTP Routines
HTTP Routines
IGMP Routines
Miscellaneous Routines
Modem Routines
PPP Routines
Serial Routines
SLIP Routines
SMTP Routines
SNMP Routines
System Functions
TCP Routines
Telnet Routines
TFTP Routines
UDP Routines
RL-CAN
RL-USB
Example Programs
Library Reference
Appendix
DNS Client
The DNS Client allows you to resolve IP addresses of internet hosts that are identified by a host name. The address is resolved using a protocol in which a piece of information is sent by a client process (executing on the local computer) to a server process (executing on a remote computer). The address resolution procedure is completed when the client receives a response from the server containing the required address.
-
DNS Client switch enables or disables the DNS Client
service in your application. It is enabled when this value is set
to 1. It should be set to 0 when the DNS Client is not used.
#define DNS_ENABLE 1
-
Cache Table size specifies the size of the DNS Cache by
defining the number of entries for the DNS Cache table. When the
IP address is resolved, it is also stored to the local cache.
When a request for resolving an IP address is received, the DNS Client first checks the local cache memory. If a valid entry is found there, the IP address is taken from the cache, and the request is not sent on to the remote DNS Server.
#define DNS_TABSIZE 20
Note
- DNS Cache entries expire after a Time to Live (TTL) timeout. This is defined by the DNS Server. The TTL value for resolved IP addresses is received in an answer packet from the DNS Server. The DNS Client manages the timeouts. When a timeout counter expires, the DNS Cache entry is deleted from the Cache.
- When the DNS client is not enabled, the ARM linker does not link the DNS support modules to your application and thus reduces the code size and memory usage.
ProductsDevelopment Tools |
Hardware & Collateral |
Downloads |
Support |
Contact |
 |
||||