The number of PTR query on BIND

[Guido Roeskens]

Hello,

Dowon Kim wrote:
> I am managing some name servers.
> Why is the number of PTR query on all my name servers always more than any other queries? 
Because a lot of spam origins from Asian Countries
(high bandwidth, low security)
Many Mail Servers which receive Mail check if a
reverse entry in DNS (PTR) for the sending host exists.
It then may check if a corresponding forward entry (A record)
exists.
> Especially, The number of PTR query on my name server in foreign country is much more than PTR query on domestic name servers.
You, your company or your clients send mail to mail servers in foreign
countries.
When they (or their DNS servers) ask for the PTR record, they use the
namserver with the lowest latency. There is a good chance that your
"foreign" nameserver has the lowest latency.
e.g. if your nameserver is in the US, chances are high that this
nameserver has the lowest latency from US (and even Europe I guess)
> Could you tell me the reason?
> 
I hope this explanation helps.
And I don't want to offend you with the remark
about spam above.
No. 1 spam source is still the US.
In Switzerland we "know" our spammers and they know
have to send their spam from the UK.
> --
> Dowon Kim kimdw at nida.or.kr
> 
> 
Guido Roeskens