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Re: [SLUG] Sendmail, dns & resolv.conf
On Thu, May 03, 2001 at 08:09:19PM +1000, The Mystical Ninja (email@example.com) wrote:
> I have a RedHat 7.0 box on a clients site handling their mail. The site uses outside DNS servers for resolving and while the network is connected to the Internet everything is fine. However, when the connection drops, we obviously can't send outside mail but we also cannot send internal email without a long wait. To send a email from firstname.lastname@example.org to email@example.com takes upto 2 minutes even though the mail server recieves mail for company.com.au. Why does sendmail insist on doing a DNS lookup on company.com.au when it set to recieve mail for that domain, and is there any setting I am missing? I'd rather not have to setup a DNS server on the mail server. The wierd thing is if the Internet connection has dropped I can rm resolv.conf so sendmail has no name servers to check, and mail seems to go through fine.
This is all part of SPAM protection and it is good that way.
What you want to do is to run you own nameserver and in
the resolv.conf you put "127.0.0.1" as the first line.
Then is the name server configuration you do something like this:
IP ADDRESSES OF YOUR NAME SERVERS UPSTREAM
query-source port 53;
IP ADDRESS RANGES OF YOU DOMAIN
That means that if YOUR namesserver cant solve it it will ask the upstream
nameserver AND receive the reply and send it back to the machine querying.
So when you internet connection is DOWN your nameserver is still able to
solve the local stuff.
This will too decrease the data transfered on your internet connection
as your nameserver (if it caches) will take up a lot of the queries.
hope it helps
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