we have 2 Boardermanager 3.5.3 proxys. when i try to access a external

site that has reciently changed its ip address. via proxy one it
resolves
ok & displays the site. when I try the same site from the 2nd proxy
it
returns.
HTTP Error 504 Gateway Time-Out
how do i clear the incorrect ip address that is being retained in the
2nd
proxy.