Typical Examples Of Dns - Planet XGS3-42000R User Manual

65.3 Typical Examples of DNS

ip domain-lookup
dns-server 219.240.250.101
dns-server 2001::1
SWITCH
As shown in fig, the switch connected to DNS server through network, if the switch want to visit sina Website,
it needn't to know the IP v4/ IP v6 address of sina Website, only need is to rec ord t he domain name of sina
Website is www.sina.com.cn. The DNS server can resolut e out the IP v4/ IP v6 address of this domain name
and send to switch, then the switch can visit sina Website correctly. The switch is configured as DNS client,
basic configurations are as below: first to enable DNS dynamic domain name resolution function on switch,
and configure DNS server address, then with some kinds of tools such as PING, the switch can get
corresponding IP v4/IP v6 address with dynamic domain name resolution function.
client
The figure above is an applic ation of DNS SE RVER. Under some circumstances, the client P C doesn't know
the real DNS SERVE R, and points to the switch instead. The s witch plays the role of a DNS SERVE R in two
steps: Enable the global DNS SERVER function, configure the IP address of the real DNS server. After the
DNS SERVER function is globally enabled, the switch will look up its local cache when receiving a DNS
request from a client PC. If there is a domain needed by the local client, it will directly ans wer the client's
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 look up in the future.
INTE RNE T
DNS CLIENT typical environment
Figure 65-3-1
SWITCH
Figure 65-3-2 DNS SERVER typical environment
INTE RNE T
65-4
DNS SERVER
IP: 219.240.250.101
IP v6: 2001::1
DNS SERVER
IP:219.240.250. 101
IP v6:2001::1