Chapter 9 Testing and Troubleshooting
Troubleshooting the Network
Cisco IronPort AsyncOS 7.5 for Email Daily Management Guide
“Drill-down” to use the
command on the top domains listed from
command returns monitoring information about email
operations relating to a specific recipient host. DNS information stored in the
AsyncOS cache and the last error returned from the recipient host are also
given. Data returned is cumulative since the last
(For more information, see Monitoring the Status of a Mail Host, page 6-18.)
command on the top domains can isolate the
performance issues with DNS resolution to the either the appliance or the
internet. For example, if the
command for the top active recipient
host shows many pending outbound connections, then try to determine if that
particular host is down or unreachable, or if the appliance cannot connect to
all or the majority of hosts.
Check firewall permissions.
The appliance may need all of the following ports to be opened in order to
function properly: ports 20, 21, 22, 23, 25, 53, 80, 123, 443, and 628. (See
Appendix C, “Firewall Information,” in the Cisco IronPort AsyncOS for
Email Configuration Guide for more information.)
Send email from the appliance on your network to
Send an email from within your network to
perform basic DNS checks on your system. And auto-responder email will
respond with the results and details of the following four tests:
DNS PTR Record - Does the IP address of the Envelope From match the PTR
record for the domain?
DNS A Record - Does the PTR record for the domain match the IP address
of the Envelope From?
HELO match - Does the domain listed in the SMTP HELO command match
the DNS hostname in the Envelope From?
Mail server accepting delayed bounce messages - Does the domain listed
in the SMTP HELO command have MX records that resolve IP addresses for
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