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  1.   Trademarks
  2. 1 Introduction
    1. 1.1 License
    2. 1.2 IwIP Version
    3. 1.3 lwIP Customization
    4. 1.4 IwIP API
      1. 1.4.1 TCP RAW APIs
      2. 1.4.2 UDP RAW APIs
    5. 1.5 lwIP Development Home Page and Support
  3. 2 Application Examples
  4. 3 Application Setup
    1. 3.1 Hardware Setup
    2. 3.2 Software Tools
  5. 4 Download and Import the Ethernet examples
  6. 5 Enet_tcpecho_server_lwip Example Overview
    1. 5.1 Build and Flash the Program
    2. 5.2 Check and Program the MAC Address
      1. 5.2.1 Using The LM Flash Programmer
      2. 5.2.2 Using the CCS
      3. 5.2.3 Using Uniflash
    3. 5.3 Configure the Terminal Window
    4. 5.4 Run the enet_tcpecho_server_lwip Example
  7. 6 Enet_tcpecho_server_static_ip_lwip Example Overview
    1. 6.1 How to Configure lwIP for Static Address
    2. 6.2 Run the enet_tcpecho_server_static_ip_lwip Example
  8. 7 Enet_udpecho_server_lwip Example Overview
    1. 7.1 Run the enet_udpecho_server_lwip Example
  9. 8 Enet_dns_lwip Example Overview
    1. 8.1 How to Configure lwIP for DNS
    2. 8.2 How to View the DNS Traffic on Wireshark
    3. 8.3 Run the enet_dns_lwip Example
  10. 9 Enet_sntp_lwip Example Overview
    1. 9.1 Run the enet_sntp_lwip Example
  11. 10Enet_tcpecho_client_lwip Example Overview
    1. 10.1 Configure the Server IP Address
    2. 10.2 Configure the SocketTest Server and Run the enet_tcpecho_client_lwip Example
    3. 10.3 Wireshark Capture for enet_tcpecho_client_lwip Example
  12. 11Enet_adcsensor_client_lwip Example Overview
    1. 11.1 Run the adcsensor_client_lwip Example
  13. 12Enet_udpecho_client_lwip Example Overview
    1. 12.1 Run the enet_udpecho_client_lwip Example
  14. 13References

8.1 How to Configure lwIP for DNS

To use DNS, there are three steps to follow:

  1. Configure or uncomment the below default #define in the lwipopts.h file. 
    #define LWIP_DNS                        1
#define DNS_TABLE_SIZE                  4
#define DNS_MAX_NAME_LENGTH             256
#define DNS_MAX_SERVERS                 2
#define DNS_DOES_NAME_CHECK             1
#define DNS_USES_STATIC_BUF             1
#define DNS_MSG_SIZE                    512
  2. Since the DNS relies on the UDP protocol, the application needs to include the below header files.
    #include “lwip/udp.h”
#include “lwip/inet.h”
#include “lwip/dns.h”
  3. Use the dns_gethostbyname() API to translate the domain names. Below is an example usage. See the enet_dns_lwip.c file for detail. 
    err = dns_gethostbyname(host_addresses[current_host], &dns_resolved_address,
                        DnsFound, NULL);
  4. Recompile the project and you are ready to run the example.