domain name system - Connectivity problems on website

We've been experiencing some connectivity problems on http://www.scirra.com. Running a DNS check:

http://dnscheck.pingdom.com/?domain=www.scirra.com

We're getting some errors:

Delegation not found at parent.

No delegation could be found at the parent, making your zone
unreachable from the Internet.

Not enough nameserver information was found to test the zone
www.scirra.com, but an IP address lookup succeeded in spite of that.

It's been ticking by nicely for many months, and we've made no changes recently except replacing expiring SSL certificates on our servers.

Problems I'm experiencing are intermittent This web page is not available errors in Chrome, where refreshing sometimes loads it.

Any ideas on what could be causing these issues?

Answer

There is an issue with the last hop to the server. Here are the results from a pathping to www.scirra.com.

$ pathping www.scirra.com


Tracing route to www.scirra.com [108.61.84.218]
over a maximum of 30 hops:

...

  3  vnn-rc0001-cr101-ae10-217.core.as9143.net [213.51.166.65]
  4  asd-tr0042-cr101-ae6-0.core.as9143.net [213.51.158.78]
  5  te0-6-1-4.rcr21.b031955-0.ams03.atlas.cogentco.com [149.14.34.173]

  6  be2499.ccr41.ams03.atlas.cogentco.com [130.117.1.149]
  7  be2038.rcr21.ams05.atlas.cogentco.com [154.54.36.134]
  8  tinet.ams05.atlas.cogentco.com [130.117.14.50]
  9  xe-2-0-2.nyc39.ip4.gtt.net [141.136.111.106]
 10  gtt-gw.ip4.gtt.net [173.241.131.238]
 11  ae1-50g.ar1.nyc3.us.as4436.gtt.net [69.31.95.194]
 12  as20473.ae7.ar1.nyc3.us.as4436.gtt.net [69.31.34.62]
 13  108.61.244.41
 14  vl329-c11-15-b2-1-sa.pnj1.choopa.net [108.61.65.62]
 15     *     108.61.84.218


Computing statistics for 375 seconds...
            Source to Here   This Node/Link
Hop  RTT    Lost/Sent = Pct  Lost/Sent = Pct  Address

...

  3   10ms     0/ 100 =  0%     0/ 100 =  0%  vnn-rc0001-cr101-ae10-217.core.as9143.net [213.51.166.65]
                                0/ 100 =  0%   |

  4   15ms     0/ 100 =  0%     0/ 100 =  0%  asd-tr0042-cr101-ae6-0.core.as9143.net [213.51.158.78]
                                0/ 100 =  0%   |
  5   10ms     0/ 100 =  0%     0/ 100 =  0%  te0-6-1-4.rcr21.b031955-0.ams03.atlas.cogentco.com [149.14.34.173]
                                0/ 100 =  0%   |
  6   11ms     0/ 100 =  0%     0/ 100 =  0%  be2499.ccr41.ams03.atlas.cogentco.com [130.117.1.149]
                                0/ 100 =  0%   |
  7    9ms     0/ 100 =  0%     0/ 100 =  0%  be2038.rcr21.ams05.atlas.cogentco.com [154.54.36.134]
                                0/ 100 =  0%   |
  8    9ms     0/ 100 =  0%     0/ 100 =  0%  tinet.ams05.atlas.cogentco.com [130.117.14.50]
                                0/ 100 =  0%   |

  9   84ms     0/ 100 =  0%     0/ 100 =  0%  xe-2-0-2.nyc39.ip4.gtt.net [141.136.111.106]
                                0/ 100 =  0%   |
 10   84ms     0/ 100 =  0%     0/ 100 =  0%  gtt-gw.ip4.gtt.net [173.241.131.238]
                                0/ 100 =  0%   |
 11   86ms     0/ 100 =  0%     0/ 100 =  0%  ae1-50g.ar1.nyc3.us.as4436.gtt.net [69.31.95.194]
                                0/ 100 =  0%   |
 12   89ms     0/ 100 =  0%     0/ 100 =  0%  as20473.ae7.ar1.nyc3.us.as4436.gtt.net [69.31.34.62]
                                0/ 100 =  0%   |
 13  ---     100/ 100 =100%   100/ 100 =100%  108.61.244.41
                                0/ 100 =  0%   |

 14   86ms     0/ 100 =  0%     0/ 100 =  0%  vl329-c11-15-b2-1-sa.pnj1.choopa.net [108.61.65.62]
                               54/ 100 = 54%   |
 15   86ms    54/ 100 = 54%     0/ 100 =  0%  108.61.84.218

Trace complete.

There is a 54% packet loss between hops 14 and 15.