And they want you to maintain the server? !!

Or are you maintaining greece.org, on either a shared or dedicated server? Not the server itself.

Noting the nameserver names are the same for both your domain and the web host, I'm guessing it's the webhost who isn't playing ball and has one nameserver offline, and according the posts above, the other poorly configured.

If you can't change webhost you do have several options... personally I'd be concerned with my domain only resolving some of the time, as it will prevent many of your "users" getting to your site too. It's not going to just be a problem for you as admin.

If you can't get the webhost to fix the problem, you can host DNS elsewhere and leave the website where it is. Generally you can host DNS with the domain registrar. I see the tech contact for your domain is listed as:

Name: Thanos Voudouris
Organization: Hellenic Electronic Center
Mailing Address: 10201 Grosvenor Place, N. Bethesda MD 20852 US
Phone: +1.2408889585
Ext:
Fax: +1.9999999999
Fax Ext:
Email:[email protected]

Do you have contact with them?

Also, just to fix the problem for yourself, you can use the hosts file on your PC as another way of mapping the domain name to the IP address (noting if you just try to access the IP address direct you often can't as the server hosts many domains and doesn't know which you're trying to access).

Uh uh!!

I just did tracert to both. No DNS problem at all. Looks to me more like a deliberate block from our addresses. Even using the IP addresses given as the tracert target at the top a browser can't access them.

C:\Users\Bob>tracert greece.org

Tracing route to greece.org [64.118.198.21]
over a maximum of 30 hops:

1 2 ms 2 ms 1 ms 192.168.1.254
2 20 ms 20 ms 23 ms b.gormless.thn.aa.net.uk [90.155.53.52]
3 * 21 ms 21 ms g.aimless.thn.aa.net.uk [90.155.53.47]
4 20 ms 20 ms 33 ms ge-4-3-6.edge5.London1.Level3.net [195.50.116.49]
5 21 ms 20 ms 21 ms ae-230-3606.edge4.London1.Level3.net [4.69.166.21]
6 21 ms 21 ms 20 ms XO-level3-1x10G.London.Level3.net [4.68.70.134]
7 109 ms 104 ms 104 ms 207.88.13.56.ptr.us.xo.net [207.88.13.56]
8 108 ms 106 ms 116 ms 207.88.12.105.ptr.us.xo.net [207.88.12.105]
9 105 ms 105 ms 105 ms te-3-0-0.rar3.washington-dc.us.xo.net [207.88.12.74]
10 104 ms 104 ms 103 ms 207.88.12.99.ptr.us.xo.net [207.88.12.99]
11 104 ms 104 ms 104 ms 216.156.16.125.ptr.us.xo.net [216.156.16.125]
12 * * * Request timed out.
13 165.117.253.98 reports: Destination net unreachable.

Trace complete.

C:\Users\Bob>tracert arktelecom.com

Tracing route to arktelecom.com [64.118.199.100]
over a maximum of 30 hops:

1 4 ms 2 ms 1 ms 192.168.1.254
2 21 ms 22 ms 20 ms b.gormless.thn.aa.net.uk [90.155.53.52]
3 * 36 ms 26 ms g.aimless.thn.aa.net.uk [90.155.53.47]
4 20 ms 20 ms 20 ms ge-4-3-6.edge5.London1.Level3.net [195.50.116.49]
5 23 ms 19 ms 20 ms ae-229-3605.edge4.London1.Level3.net [4.69.166.17]
6 21 ms 21 ms 22 ms XO-level3-1x10G.London.Level3.net [4.68.70.134]
7 104 ms 104 ms 105 ms 207.88.13.56.ptr.us.xo.net [207.88.13.56]
8 106 ms 107 ms 105 ms 207.88.12.105.ptr.us.xo.net [207.88.12.105]
9 106 ms 107 ms 107 ms te-3-0-0.rar3.washington-dc.us.xo.net [207.88.12.74]
10 115 ms 117 ms 109 ms 207.88.12.99.ptr.us.xo.net [207.88.12.99]
11 104 ms 104 ms 104 ms 216.156.16.125.ptr.us.xo.net [216.156.16.125]
12 165.117.253.98 reports: Destination net unreachable.

Trace complete.

C:\Users\Bob>

Edited by RobertoS (Sat 20-May-17 23:20:04)

Neither greece.org or arktelecom.com resolve on TalkTalk's automatically assigned nameservers for me.

How have you tested that?

I used tracert at a command line prompt. That shows on the first line the IP address it has found, as you can see in my earlier post. Then a few hops down the line it hits a brick wall.

Using a browser all you see is the brick wall. But behind the scenes the DNS servers had supplied the browser with the correct target address.

Beware of traceroute for connectivity diagnostics as it can give misleading answers.

traceroute www.greece.org
1 <CENSORED> 0.418 ms 0.401 ms 0.391 ms
2 losubs.subs.bng2.th-lon.zen.net.uk (62.3.80.21) 12.116 ms 12.128 ms 12.123 ms
3 ae1-183.cr2.th-lon.zen.net.uk (62.3.86.82) 12.120 ms 12.110 ms 12.101 ms
4 xe-8-2-2.cr0-lon1.ip4.gtt.net (77.67.66.225) 12.079 ms 12.070 ms 12.069 ms
5 xe-0-0-6.cr8-nyc3.ip4.gtt.net (89.149.129.21) 85.750 ms xe-1-1-1.cr8-nyc3.ip4.gtt.net (141.136.105.41) 85.712 ms xe-0-0-6.cr8-nyc3.ip4.gtt.net (89.149.129.21) 85.734 ms
6 206.111.13.84.ptr.us.xo.net (206.111.13.84) 85.718 ms 85.333 ms 85.323 ms
7 207.88.13.34.ptr.us.xo.net (207.88.13.34) 92.905 ms 88.442 ms 88.424 ms
8 207.88.12.105.ptr.us.xo.net (207.88.12.105) 92.278 ms 92.274 ms 92.253 ms
9 te-3-0-0.rar3.washington-dc.us.xo.net (207.88.12.74) 89.488 ms 89.479 ms 89.469 ms
10 207.88.12.99.ptr.us.xo.net (207.88.12.99) 89.447 ms 87.941 ms 87.941 ms
11 216.156.16.125.ptr.us.xo.net (216.156.16.125) 87.921 ms 87.902 ms 89.226 ms
12 165.117.253.98 (165.117.253.98) 92.938 ms 92.937 ms 91.709 ms
13 * * *
14 * * *
15 * * *
16 * * *
17 * * *


Yet entering www.greece.org works perfectly normally here (though be cautioned, whilst ZEN is my ISP, I do not use their DNS servers.)

Telling traceroute to simulate a normal http connect you get a different result:
traceroute www.greece.org -T -p80
traceroute to www.greece.org (64.118.198.21), 30 hops max, 60 byte packets
1 <CENSORED> 0.352 ms 0.322 ms 0.324 ms
2 losubs.subs.bng2.th-lon.zen.net.uk (62.3.80.21) 12.006 ms 12.022 ms 12.016 ms
3 ae1-183.cr2.th-lon.zen.net.uk (62.3.86.82) 13.205 ms 13.193 ms 13.155 ms
4 xe-8-2-2.cr0-lon1.ip4.gtt.net (77.67.66.225) 11.943 ms 12.923 ms 12.923 ms
5 xe-0-0-6.cr8-nyc3.ip4.gtt.net (89.149.129.21) 85.439 ms xe-1-1-1.cr8-nyc3.ip4.gtt.net (141.136.105.41) 85.447 ms 85.439 ms
6 206.111.13.84.ptr.us.xo.net (206.111.13.84) 88.013 ms 86.566 ms 86.562 ms
7 207.88.13.34.ptr.us.xo.net (207.88.13.34) 114.113 ms 102.432 ms 102.401 ms
8 207.88.12.105.ptr.us.xo.net (207.88.12.105) 92.371 ms 92.367 ms 91.185 ms
9 te-3-0-0.rar3.washington-dc.us.xo.net (207.88.12.74) 89.896 ms 89.898 ms 89.887 ms
10 207.88.12.99.ptr.us.xo.net (207.88.12.99) 88.605 ms 88.807 ms 88.787 ms
11 216.156.16.125.ptr.us.xo.net (216.156.16.125) 88.772 ms 88.649 ms 88.667 ms
12 165.117.253.98 (165.117.253.98) 92.441 ms 92.424 ms 93.681 ms
13 64.118.201.6 (64.118.201.6) 92.398 ms 93.679 ms 93.562 ms
14 hec2.greece.org (64.118.198.21) 209.895 ms 209.881 ms 199.722 ms

Possibly 64.118.201.6 is some kind of firewall which drops the ICMP packets that windows uses by default and the UDP packets linux uses by default.

I was merely using it to prove or disprove the working or not of my DNS servers, and suggest others with the problem may find it useful.

I believe that although neither IE11 or Chrome can reach the two sites in question in the OP, the fact that tracert ascertains a target address and a route to it shows there is nothing wrong with the DNS servers.

You warn against using it as a diagnostic, but surely it is valid for that purpose?

Many people have been trying or suggesting all sorts of DNS server adjustments. I suspect they are all barking up the wrong tree.

My router has been assigned 79.79.79.77 and 79.79.79.78 as it's DNS servers by TT.

So using NS lookup, first looking up google.com to show it's working.

$ nslookup
>
> server 79.79.79.77
Default server: 79.79.79.77
Address: 79.79.79.77#53
>
>
> google.com
Server: 79.79.79.77
Address: 79.79.79.77#53

Non-authoritative answer:
Name: google.com
Address: 216.58.210.46
Name: google.com
Address: 216.58.210.46
Name: google.com
Address: 216.58.210.46
>
>
> greece.org
;; connection timed out; no servers could be reached
>
>
> arktelecom.com
;; connection timed out; no servers could be reached
>

Then switching to the other nameserver:

> server 79.79.79.78
Default server: 79.79.79.78
Address: 79.79.79.78#53
>
> google.com
Server: 79.79.79.78
Address: 79.79.79.78#53

Non-authoritative answer:
Name: google.com
Address: 216.58.210.46
Name: google.com
Address: 216.58.210.46
Name: google.com
Address: 216.58.210.46
>
>
> greece.org
;; connection timed out; no servers could be reached
>
> arktelecom.com
;; connection timed out; no servers could be reached

Edited by sills (Mon 22-May-17 10:31:27)

I haven't clue what you are trying to say or prove. Neither seem to ba at all relevant to anything I have posted, and in particular that the DNS servers people are using are not the problem and playing with them is a waste of time.

Please leave it. I made a perfectly sensible and I believe useful post and you keep going on and on and on.

In reply to a post by RobertoS:

Please leave it. I made a perfectly sensible and I believe useful post and you keep going on and on and on.

I made one reply, in response to a direct question from you. I won't bother again, it was obviously a waste of time.