Website fails to connect

 I have SBS2011 network and no one can open this website from inside.
 I can open this website from any computer from outside of our network.
 in SBS2011 DNS Manager, I don't have any DNS servers listed so that it uses root hints.
 We do have a backup DNS server on the same network and each workstation PC has two Name servers: &  for example.
 Where do I begin troubleshooting this?
 No one has reported the same kind of problem before.

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atlas_shudderedSr. Network EngineerCommented:
On one of your internal workstations, change the DNS settings to the global roots and and try to resolve and hit the site.

If you are able to connect, you need to start looking toward DNS.  If not, you will need to start looking toward a firewall/proxy issue.

Make that determination and post up.

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Step 1.
Identify what address the domain name points to internally - from a command prompt run nslookup www.<domain>.com

Step 2.
Determine how traffic is routed to that destination ip - from a command prompt run tracert <ip address from command above>

Step 3.
Resolve the issue - based on the information from the above commands we can determine what steps to take.
David FavorLinux/LXD/WordPress/Hosting SavantCommented:
Likely problem is what you're calling Backup DNS Servers.

These servers should only be caching servers, so your internal lookups match your external lookups.

Be sure you have forwarders setup to either global root servers or better Google's stable servers, which are + + tend to always be up.

Follow becraig's advice. Run an nslookup for your domain explicitly pointing to + then both your Backup DNS Servers.

If there's any difference between what Google ( returns + your Backup DNS Servers, then best fix this broken config.
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sgleeAuthor Commented:
A"Likely problem is what you're calling Backup DNS Servers." --> OK. I will start working on it this evening and report back.
David FavorLinux/LXD/WordPress/Hosting SavantCommented:
Follow becraig's suggestion.

The nslookup tool can surface problems instantly.
sgleeAuthor Commented:
Kuebix Home PageSorry about late reply.
In internet browser, home page shows up after several minutes of delay in broken parts as seen in the screenshot.

Here are results of NSLOOKUP and TRACERT:

(1) nslookup

Server:  DC1.DC.local


(2) Tracert


racing route to []
ver a maximum of 30 hops:

 1     3 ms     1 ms     1 ms
 2     *        *        *     Request timed out.
 3    15 ms    24 ms    19 ms [

 4    21 ms    17 ms    12 ms []
 5    15 ms    18 ms    12 ms []
 6    11 ms    15 ms    10 ms []
 7    17 ms    12 ms    11 ms []
 8    13 ms    13 ms    12 ms []
 9    26 ms    22 ms    22 ms []

10    31 ms    20 ms    21 ms []

11    24 ms    23 ms    26 ms
12    23 ms    24 ms    24 ms
13    35 ms    23 ms    25 ms
14    32 ms    34 ms    38 ms
15    44 ms    42 ms    49 ms
16    76 ms    83 ms    74 ms
17    77 ms    75 ms    74 ms
18     *        *        *     Request timed out.
19     *        *        *     Request timed out.
20     *        *        *     Request timed out.
21     *        *        *     Request timed out.
22     *        *        *     Request timed out.
23     *        *        *     Request timed out.
24     *        *        *     Request timed out.
25     *        *        *     Request timed out.
26     *        *        *     Request timed out.
27    95 ms    77 ms    75 ms []

Trace complete.
atlas_shudderedSr. Network EngineerCommented:
Is knology your ISP?
Do you manage your firewall or does someone else (isp, third party, another admin)?
Run a wire shark on the machine you are testing from. You are clearly getting resolution and packets but the behavior would indicate fragmenting, retrans, etc.
sgleeAuthor Commented:
WOW (Wide Open West) is my ISP. I have Cisco router, but I do not have firewall. The strange thing is that this is only website with problem and there are 15 users surfing the internet daily. If firewall or ISP is problem, then shouldn’t we experience the same issue on other websites?
I do not know what the wire shark is or does. Can you provide URL?
I'd also suggest getting fiddler from
Install it in a machine that cannot access the site.
Once installed start monitoring browser traffic and share the logs or even a screenshot of the results.
sgleeAuthor Commented:
"Install it in a machine that cannot access the site." --> I will install it on a PC, but the problem with the site is happening to ALL computers on the network.
atlas_shudderedSr. Network EngineerCommented:
WOW and knology are same thing.

Wire shark is a packet sniffer.

And not necessarily across all websites.  May be something particular to docs.

Pull the wire shark capture and let's have a look.
sgleeAuthor Commented:
I installed Fiddler and things are scrolling up busily on the left window pane. What am I supposed to do here?
sgleeAuthor Commented:
wire sharkHow do I set this up?
sgleeAuthor Commented:
I found the problem.
In Cisco router configuration, I created BLOCK LIST where I block certain IP addresses using DENY command like below:
deny ip any
deny ip any
.... etc

This cause some websites located overseas (southest Asia and Latin America) being blocked when users try to visit a couple of websites.
After this BLOCK LIST was removed, the problem is solved.
I will have to be more specific with IP addresses in my BLOCKLIST.

Thanks you all for your help.
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