PLANET XGS3-24042 - Manual (Page 636)

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request; otherwise, the switch will relay the request to the real DNS server, pass the reply from the DNS
Server to the client and record the domain and its IP address for a faster lookup in the future.
Switch configuration for DNS CLIENT:
Switch(config)# ip domain-lookup
Switch(config)# dns-server 219.240.250.101
Switch(config)# dns-server 2001::1
Switch#ping host www.sina.com.cn
Switch#traceroute host www.sina.com.cn
Switch#telnet host www.sina.com.cn
Switch configuration for DNS SERVER:
Switch(config)# ip domain-lookup
Switch(config)# dns-server 219.240.250.101
Switch(config)# dns-server 2001::1
Switch(config)# ip dns server
74.4 DNS Troubleshooting
In configuring and using DNS, the DNS may fail due to reasons such as physical connection failure or wrong
configurations. The user should ensure the following:

First make sure good condition of the TACACS+ server physical connection;
 Second all interface and link protocols are in the UP state (use “show interface” command);
 Then please make sure that the DNS dynamic lookup function is enabled (use the “ip
domain-lookup” command) before enabling the DNS CLIENT function. To use DNS SERVER
function, please enable it (use the “ip dns server” command);
 Finally ensure configured DNS server address (use “dns-server” command), and the switch can
ping DNS server;
 If the DNS problems remain unsolved, please use debug DNS all and other debugging command
and copy the DEBUG message within 3 minutes, send the recorded message to the technical
service center of our company.