Bad Referal

[Y2KNET]

I am getting of lot of security violation message like:

Apr  3 06:24:05 ns1 named[137]: bad referral (174.147.192.in-addr.arpa !< 182.174.147.192.in-addr.arpa) from [192.147.174.26].53
Apr  3 04:25:38 ns1 named[137]: bad referral (66.241.207.in-addr.arpa !< 14.66.241.207.in-addr.arpa) from [129.250.35.32].53
Apr  3 03:58:45 ns1 named[137]: bad referral (157.209.in-addr.arpa !< 110.157.209.in-addr.arpa) from [192.67.14.17].53
Apr  3 01:10:45 ns1 named[137]: bad referral (66.241.207.in-addr.arpa !< 25.66.241.207.in-addr.arpa) from [192.67.14.16].53


Can someone give me more in formation on bad referral and how to secure 
from them.

I will strongly appreciate.

Abu Umair