F9 DNS servers not updating?

[#1]

I've now started having some issues with the old Force 9 DNS servers
212.159.13.50
212.159.13.49
212.159.6.9
The web site I'm trying to reach is www.marapets.com other people can reach it but I cannot. I can reach other web sites just fine. I've tried cleaning out the IE web caches. Vista connection diagnostics said "the host name cannot be found in the DNS".

[#2]

I got the webpage up first go, but you seem to be right.
nslookup www.marapets.com 212.159.13.50
Server:  pth-cdns02.plus.net
Address:  212.159.13.50
*** pth-cdns02.plus.net can't find www.marapets.com: Server failed
nslookup www.marapets.com 212.159.13.49
Server:  pth-cdns01.plus.net
Address:  212.159.13.49
*** pth-cdns01.plus.net can't find www.marapets.com: Server failed
nslookup www.marapets.com 212.159.6.9
Server:  ptn-cdns01.plus.net
Address:  212.159.6.9
*** ptn-cdns01.plus.net can't find www.marapets.com: Server failed
But 212.159.6.10 gets the answer:
nslookup www.marapets.com 212.159.6.10
Server:  ptn-cdns02.plus.net
Address:  212.159.6.10
Non-authoritative answer:
Name:    www.marapets.com
Addresses:  64.56.73.17, 64.56.73.21, 64.56.73.31, 64.56.73.32
          64.56.73.33, 64.56.73.34, 64.56.73.39, 64.56.73.40, 64.56.73.41
          64.56.73.42, 64.56.73.43, 64.56.73.44, 64.56.73.50, 64.56.73.83
          64.56.73.2, 64.56.73.3, 64.56.73.4, 64.56.73.5, 64.56.73.7
          64.56.73.8, 64.56.73.9, 64.56.73.10, 64.56.73.14, 64.56.73.15
          64.56.73.16
So PlusNet does seem to have a problem resolving www.marapets.com dependent on the DNS used!

[#3]

yeah i can reach it on it's IP address 64.56.73.33 but not through the DNS name
I'll try that 212.159.6.10 DNS, gota keep the kids happy 

[#4]

Ah, this answers the questions I raised in the thread here.
All seems to working OK for me at the moment though.

[#5]

Yes Bob, all seems to have returned to normal.  It was around 16:15 this afternoon that the 3 DNSs above were not able to resolve www.marapets.com although 212.159.6.10 could.  However, all four DNSs were able to resolve www.bbc.co.uk at that time.  Why?  No idea!

[#6]

They were not resoving since early in the morning but they did come back after we mentioned it on the forums (around 18:45) so i don't know if someone your end gave it a kick
I've seen two other threads moaning about DNS issues so if no-one tweaked somethin then it may be worth keeping an eye on as it seems to have a very slow update.