Is my BIND Server's Cache Poisioned ?

[Barry Margolin]

In article <d9vige$jp6$1 at sf1.isc.org>, Joe Shen <joe_hznm at yahoo.com.sg> 
wrote:

> Hi,
> 
> I met a strange problem with my cache server, which
> runs BIND9.3.1.
> 
> In past days, our customers complaint that three
> domain names (www.hangzhou.gov.cn, www.zpepc.com.cn)
> could not be resolved frequently. I checked on the
> cache server and found, when the cache server could
> not resolve www.hangzhou.gov.cn (www.zpepc.com.cn) I
> can solve the problem by running "rndc flush". 
> 
> The debugging output of named process has the
> following output when it could not resolve
> www.hangzhou.gov.cn.
> 
> Do that mean my cache server is poisioned for these
> two domain name? 

The authoritative servers for the hangzhou.gov.cn domain do not have A 
records for the nameserver hostnames.

The NS records for zpepc.com.cn are aliases rather than primary 
hostnames.  This can cause problems like this.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***