Exchange (and IIS SMTP) use TCP 53 for DNS queries as well, not just UDP.
Depending on the number of SMTP virtual servers doing DNS lookups for
delivery, what one considers "general" will vary.
t
----- Original Message -----
From: "John Hally" <JHally@epnet.com>
To: <pen-test@securityfocus.com>
Sent: Friday, November 11, 2005 5:35 AM
Subject: DNS ACL ?
Hello All,
I need a sanity check regarding DNS ACLs. For external facing DNS servers
you need to allow only udp/53 inbound, correct? I know tcp/53 is used for
zone transfers and requests/replies greater than a certain size, but they
shouldn't typically happen for general dns queries correct?
Thanks in advance!
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