We use our own RBL in cPanel. We found that sometimes it catches the IP by the RBL, sometimes it shows DNS lookup error. The RBL server is not busy at all, and we have RBL dns entry in the cpanel server host file. Any idea why the DNS lookup timeout? Thank you.
2014-05-20 14:18:03 DNS list lookup defer (probably timeout) for 129.64.xx.xx.rbl.domain.com: assumed not in list
2014-05-20 14:18:03 DNS list lookup defer (probably timeout) for 129.64.xx.xx.rbl.domain.com: assumed not in list
2014-05-20 14:18:03 DNS list lookup defer (probably timeout) for 129.64.xx.xx.rbl.domain.com: assumed not in list
2014-05-20 14:19:07 DNS list lookup defer (probably timeout) for 44.22.xx.xx.rbl.domain.com: assumed not in list
2014-05-20 14:19:08 DNS list lookup defer (probably timeout) for 44.22.xx.xx.rbl.domain.com: assumed not in list
2014-05-20 14:19:08 DNS list lookup defer (probably timeout) for 44.22.xx.xx.rbl.domain.com: assumed not in list