my network structure is:
proxy server 1(nginx)-->proxy server2(nginx)-->web server

proxy server2 has dynamic ip address. the ip address will be changed untime. so i use one domain for it: p2.domain.com.

but proxy server1(nginx) has been cached the ip of domain: p2.domain.com. so when the new ip was assigned to p2.domain.com, but proxy server1(nginx) still has old ip address.

i have searched on google, somebody said that nginx will cache the dns entry for 300 seconds(5minutes), but after 5 minutes ,event after 5 hours , the proxy server1(nginx) still has old ip address,

please help me, any ideas will be appreciated.

thank you