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Exchange web mail server couldn't accessing from few ISP

We have recently installed active-active failover with two asa5520. After that we observed that our exchange server not accessing from outside through few ISP, but it can accessed from other few ISP also. Right now we are accessing internet with one ISP.
Static NAT configuration on the Cisco ASA is:
static (inside,outside) 63.219.x.yz 172.16.3.3 netmask 255.255.255.255

Our mail server is Exchange server based. NAT is working other wise we couldn't access the web mail server from any ISP from outside. We couldn't understand what is the problem either it is happening through our ISP or ASA or mail server.

Please give us some solutions asap.

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futurenetwings
Asked:
futurenetwings
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1 Solution
 
Raj-GTSystems EngineerCommented:
It sound like a DNS propagation issue to me. If you have changed the public IP addresses, it may take up-to 48 hours for DNS propagation. You can test this by running nslookup against the ISPs DNS Servers to verify your webmail's A record is correct.
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futurenetwingsAuthor Commented:
But earlier we had used the static public with another ASA and that time it was worked fine. Is it really DNS propagation error..
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Raj-GTSystems EngineerCommented:
Are you able to connect to your webmail using the public IP from all ISPs concerned?
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futurenetwingsAuthor Commented:
Ttoday suddenly problem disappear and all outside users are able get the acees of our Webmail server from different ISP. Then we have again shifted to failover Cisco ASA from single ASA because we have 3 Cisco ASA, then we had faced the same problem then we observed that some specific branches are not able to access from the Web mail server but some braches are able to access the server. Is it the issue of DNS propagation because we couldn't change the Public and LAN IP address in the failover bundle.
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Raj-GTSystems EngineerCommented:
Yes, it does sound more like DNS propagation. You should ideally allow 48hours for any DNS changes to take affect throughout the internet.
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futurenetwingsAuthor Commented:
Hi Problem solved....Thanks a lot.
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Raj-GTSystems EngineerCommented:
I beleive I answered the question; unless futurenetwings: objects, the points should be assigned to my answer.
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