I am experiencing a strange behavior of DNS servers at OVH / Cloudflare. I came here hoping to find some help or an idea of the source of the problem.
I am not comfortable with English which is not my native language so I will try to summarize.
I have 3 dedicated Windows Server 2016 physical servers.
On 2 servers, I have 8 CentOS 7 virtual machines (Hyper-V).
The 8 CentOS VMs communicate with an API on the 3rd Windows machine. This 3rd machine has a web server (II7) and has a domain name pointing to an API (.Net MVC).
Until yesterday everything worked well for 1 year and a half. But today the 8 CentOS machines no longer recognize the dns domain of the Windows machine that contains the web server.
However :
The 8 virtrual machines can make DNS request for any other domain with success.
Any other machine can point the domain of 3rd Windows machine except these 8 machines.
This is not a DNS server problem ?
All machines (physical and virtual) use the host's DNS (OVH). The domain name is at Cloudflare but does not have a proxy (just a classic A record).
I tried on CentOS virtual machines to put Cloudflare DNS 1.1.1.1 and 1.0.0.1. But still the same problem.
When I make a DNS request from one of the VMs I have this message: host *****. Com not found: 2 (SERVFAIL Error)
Yet if I make the same request from any other computer (even the physical machine on which the virtual machines are located) with the same DNS server it works.
It looks like my virtual machines can not access the DNS server, but if I make a request to another domain it works. And even if I change DNS server the same problem occurs !
I am completely lost and I do not see where the problem may come from.
I specify that before this malfunction no change was made neither on the domain, nor at Cloudflaire nor on the servers. Everything had been working for a year and a half.
Thank you for your help.
Mayzz.
Related
1 - I have installed a fresh Windows server 2019.
2 - Got to fixed IP 192.168.10.254 and DNS server ect ...
I used 8.8.8.8 and 114.114.114.114 for DNS
3 - Went through some "guide" to setup AD, rebooted and then logged on under the Administrator account in my domain as mydomain.com/Administrator
Now how do I make other machines join the domain to mydomain.com??
When I logged the normal machine, tried to change it from my computer, it couldn't find the mydomain.com, saying something with the DNS problem....
I did some search, look like I should have set up the server DNS as my server IP address? like
fixed IP 192.168.10.254 as well as DNS 192.168.10.254 ???
I did try something like this, but then the server would not have internet access to the www.
It would only have local lan access. I am not sure what the problem seem to be....
Also, all machines in the LAN goes through a DHCP router already. Would that be an issue too?
I am running a Hyper-V lab for a client to test the functionality of a Powershell script and due to memory constraints, I would like to move my file and database VM servers off of my main desktop PC to my laptop. I set up Hyper-V on the laptop, and successfully exported/imported the VM's into the other Hyper-V server. I can boot them, all the configuration and files are intact however, I am predictably having trouble reconnecting to the domain they were a part of prior to the move. I understand I need an External virtual switch to handle that communication, as internal and private will not reach outside of the Hyper-V server they reside in. Obviously I would prefer to not use an external, but this is strictly to continue testing. I've trouble-shooted entering different DNS server values from the client machine's IPv4 properties and changing the virtual switch to External for the existing Hyper-V server, and re-register the DNS records on the DC. All result in the same error when I try to connect to the domain: "(error code 0x0000232B RCODE_NAME_ERROR) The query was for the SRV record for _ldap._tcp.dc."... "The DNS SRV records required to locate a AD DC for the domain are not registered in DNS".
In summary, I want to move a VM from the first server listed to the second, and then re-connect to the domain they were part of previously. Both machines are just running Windows 10, not Windows Servers, if that matters. Another note, I can do remote sessions from the desktop to the laptop just fine which would lead to believe this is not related to a firewall. Thanks!
The best it to set up a VLAN. If you can't do that, change the network class of your AD lab machine (192.168.55.x ?) to another in order to avoid conflicts.
Your DNS server has to be AD to make your machines connecting to it.
And last but not least, if you're on 2 different hyperV servers, you have to use external switch in hyperV:
https://redmondmag.com/articles/2018/05/04/hyper-v-private-networks.aspx
I need to connect to a Windows Server 2003 machine at work from a Windows 7 machine at home via remote deskop. The problem is, the server is set up so that only a very restricted range of IP addresses is allowed to connect to the server. For a few weeks I will be unable to physically access the machine to change these settings, so I'm screwed unless I can somehow spoof my own IP address into one that the server allows.
I know this sounds shady and variations on this question have probably been asked a million times, but it's not like I need to break into this server. I have full administrator rights to the machine, I just can't connect to the machine from outside the work network.
Is there any way to do this? Thanks for any help.
I've received a few messages from users of my site that they can not access it from home.
They can access the server from the IP, but not by the domain name.
I think it has something to do with the way my DNS is configured. I setup my own DNS server about 4 years ago on my server, which I probably should not have done, and I'm not sure if everything is configured correctly. There are plenty of people who can access the site without any problems, but some users get 'server can not be found'.
Server Details: Windows 2003 co-located server at a small local hosting company.
Are there good tools or sites that can test and provide configuration recommendations? How do I test this problem when it works fine for me and so many other users? What type of questions should I ask users that can't access the site?
Can I provide / point to another DNS server that can be used if the first server isn't working?
Thanks!
Nevertheless here some pointers:
Questions that you can ask the users:
Run the following command: nslookup test.company.com. The result should be the IP they could access by IP. If it's a wrong IP or no IP, then this hostname A / CNAME record isn't propagated correctly to the outside world.
It could be a ipv4/v6 problem. Maybe the DNS resolves to a ipv6 IP by AAAA record and your ISP (or any provider inbetween) doesn't support ipv6 correctly yet. Under windows, you can ping -6 or ping -4 to see if it resolves to anything at all.
Possible workaround:
Tell your users to hardcode the IP of your server into their HOSTS file...
DNS problems are usually lying at the companies infrastructure though (e.g. not propagating the DNS notifications correctly, wrong DNS servers at your registrar, wrong DNS configuration on your DNS server...)
There's an excellent on-line resource to verify your DNS settings: intoDNS.com
If you think the problem is in your DNS server and you don't need it this way anyway, you can just turn your DNS to any DNS hosting - see my biased list. Setup your DNS records from scratch with any DNS provider and tell your domain registrar to use that provider nameservers. Often registrars themselves provide DNS servers as well.
As for questions to ask users, Khoi explained everything.
I create a local network between my physical machine (windows) and my virtual machine (Fedorat)
I installed xampp on fedorat and I want to access my web application located in / opt / lampp / htdocs / MyApplication from my physical machine by ip address of the virtual machine
http://192.168.0.2/
But its not working
What changes must I do that on xampp to make it accessible
Is your webserver running and is it possible to access the webserver locally (from your Fedora VM)?
What do you mean by not working? There are so many things that could be wrong... Do you receive a 404? Timeout? Are your machines on the same subnet? Are you able to ping your Fedora machine from Windows?
Had a similar problem once. In my case, it was because of firewall settings.
Try connecting your own machine to a LAN access point in the same router as the VM is connected.
I don't have much tech. background, but maybe if you narrow it to this specific case, someone else can help you.
Cheers.
I ping my VM from my physical machine and it works very well
How long have I install wamp on my physical machine and I set up for access to local network and I accessed from my VM
So the network between two machines running very well
my question is not about the establishment of networks between the two machines but rather how to configure XAMPP that it is accessible by
other machine in network
(I was already a problem on windows with wamp parail I solved by configuring wamp but I recall more of what I did)