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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

8.3 Run the enet_dns_lwip Example

As expected, running this example prints the four IP addresses of the corresponding websites on the terminal window. For more details, look at the Wireshark capture particularly for www.google.com.

  • In the highlighted box 1 and box 2 of the Wireshark capture in Figure 8-3, four DNS packets are observed corresponding to the four websites.
  • The source address of the transaction is from the IP address 192.168.254.254. This happens to be the IP address of the router of the home network to which this application is run from. A smart router normally will act as the DNS server and store the past visited domain names in it cache for fast retrieval.
  • In box 3, the returned IP address for www.google.com is 172.217.1.132. You can confirm by typing this address on your browser’s URL field and it should lead you to the Google website.
  • In box 4, the IP address is expressed as a 32-bit binary value equal to 0xACD90184. The 0xAC is equal to decimal 172, the 0xD9 is equal to decimal 217 and likewise for the rest.
GUID-20210301-CA0I-MT7D-ZC5J-XH2M2KXSBJGM-low.png Figure 8-2 Enet_dns_lwip Output
GUID-20210301-CA0I-SHF4-LTZB-VGFVQCHW1D0S-low.png Figure 8-3 Wireshark Capture for Enet_dns_lwip