Website fails to connect

sglee
sglee used Ask the Experts™
on
Hi,
 
 I have SBS2011 network and no one can open this website https://www.kuebix.com 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: 192.168.1.10 & 192.168.1.11  for example.
 Where do I begin troubleshooting this?
 No one has reported the same kind of problem before.

Thanks.
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Sr. Network Engineer
Commented:
On one of your internal workstations, change the DNS settings to the global roots 4.2.2.1 and 4.2.2.2 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.
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 FavorFractional CTO
Distinguished Expert 2018

Commented:
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 8.8.8.8 + 8.8.4.4 + tend to always be up.

Follow becraig's advice. Run an nslookup for your domain explicitly pointing to 8.8.8.8 + then both your Backup DNS Servers.

If there's any difference between what Google (8.8.8.8) returns + your Backup DNS Servers, then best fix this broken config.
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Author

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 FavorFractional CTO
Distinguished Expert 2018

Commented:
Follow becraig's suggestion.

The nslookup tool can surface problems instantly.

Author

Commented:
Kuebix Home PageSorry about late reply.
In internet browser, https://www.kuebix.com 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 kuebix.com

C:\Users\User>nslookup kuebix.com
Server:  DC1.DC.local
Address:  192.168.1.9

Name:    kuebix.com
Address:  35.185.248.37

(2) Tracert

C:\Users\User>Tracert 35.185.248.37

racing route to 37.248.185.35.bc.googleusercontent.com [35.185.248.37]
ver a maximum of 30 hops:

 1     3 ms     1 ms     1 ms  192.168.1.1
 2     *        *        *     Request timed out.
 3    15 ms    24 ms    19 ms  dynamic-76-73-172-225.knology.net [76.73.172.225

 4    21 ms    17 ms    12 ms  76-73-167-196.knology.net [76.73.167.196]
 5    15 ms    18 ms    12 ms  76-73-167-201.knology.net [76.73.167.201]
 6    11 ms    15 ms    10 ms  76-73-167-198.knology.net [76.73.167.198]
 7    17 ms    12 ms    11 ms  76-73-166-126.knology.net [76.73.166.126]
 8    13 ms    13 ms    12 ms  76-73-166-125.knology.net [76.73.166.125]
 9    26 ms    22 ms    22 ms  user-24-214-131-160.knology.net [24.214.131.160]

10    31 ms    20 ms    21 ms  static-76-73-191-226.knology.net [76.73.191.226]

11    24 ms    23 ms    26 ms  206.41.110.37
12    23 ms    24 ms    24 ms  108.170.243.197
13    35 ms    23 ms    25 ms  72.14.232.109
14    32 ms    34 ms    38 ms  72.14.232.70
15    44 ms    42 ms    49 ms  209.85.251.139
16    76 ms    83 ms    74 ms  216.239.49.135
17    77 ms    75 ms    74 ms  216.239.46.175
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  37.248.185.35.bc.googleusercontent.com [35.185.248.37]

Trace complete.
atlas_shudderedSr. Network Engineer
Commented:
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.

Author

Commented:
@Atlas
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 fiddlertool.com
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.

Author

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 Engineer

Commented:
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.

Author

Commented:
fiddler@BeCraig
I installed Fiddler and things are scrolling up busily on the left window pane. What am I supposed to do here?

Author

Commented:
wire sharkHow do I set this up?

Author

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 5.0.0.0 0.255.255.255 any
deny ip 31.0.0.0 0.255.255.255 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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