Within our office, we have a local server running DNS, for internal related "domains", (e.g. .internal, .office, .lan, .vpn, etc.). Randomly, only the hosts configured with those extensions will stop resolving on the Windows-based workstations. Sometimes it'll work for a couple weeks without issue on one machine, then suddenly stop working, or it'll happen on another 15 times per day. It's completely random for all workstations.
When troubleshooting, I have opened up a command prompt, and issued various nslookup commands for some of these hosts, and they resolve, however I've been told that nslookup uses different "libraries" for name resolution than other applications such as web browsers, email clients, etc.
The only solution thus far, is manually restarting the Windows DNS Client on each workstation when this happens. Issuing the ipconfig /flushdns command multiple times helps every now and then, but is not successful enough to even attempt before restarting the DNS Client.
I have tried two different DNS servers; BIND9, and Windows Server 2003 R2 DNS, and the behavior is the same.
We have a single Netgear JGS524 switch all workstations and servers are connected to within the office, and a Linksys SR224G switch in another department with workstations attached.
In this particular situation, it appears that Windows will randomly start using a secondary name server instead of the primary, even if the primary is available.
My solution: remove the secondary. This is not a great solution as it obviously will kill the whole name resolution if this single name server goes down, but given this network is small and name resolution isn't mission critical (read: it can go down for an hour), this solution is acceptable.
Related
I have a slight problem bit of the back story. recently ive been trying to test out univention which is a linux distribution with the goal of being able to replace Microsoft active directory.
I tested it locally and all went reasonably well after a few minor issues i then decided to test it remotely as the company wants to allow remote users to access this so i used myhyve.com to host it and its now been setup successfully and works reasonably well.
however
my main problem is DNS based as when trying to connect to the domain the only way windows will recognize it is by editing the network adapter and setting ip v4 dns server address to the ip address of the server hosting the univention active directory replacement. although this does allow every thing to work its not ideal and dns look up on the internet are considerably longer. i was wondering if any one had any ideas or have done something similar and encountered this problems before and know a work around. i want to avoid setting up a vpn if possible.
after initially registering the computer on the domain i am able to remove the dns server address and just use a couple of amendments to the HOST file to keep it running but this still leads to having issues connecting to the domain controller sometimes and is not ideal. any ideas and suggestions would be greatly received.
.Michael
For the HOST entries, the most likely issue is, that there are several service records a computer in the domain needs. I'm not sure, whether these can be provided via the HOST file or not but you'll definitely have authentication issues if they are missing. To see the records your domain is using issue the following commands on the UCS system.
/usr/share/univention-samba4/scripts/check_essential_samba4_dns_records.sh
For the slow resolution of the DNS records there are several points where you could start looking. My first test would be whether or not you are using a forwarder for the web DNS requests and whether or not the forwarder is having a decent speed. To check if you are using one, type
ucr search dns/forwarder
If you get a valid IP for either of the UCR Variables, dns/forwarder1, dns/forwarder2 or dns/forwarder3, you are forwarding your DNS requests to a different Server. If all of them are empty or not valid IPs then your server is doing the resolution itself.
Not using a forwarder is often slow, as the DNS servers caching is optimized for the AD operations, like the round robin load balancing. Likewise a number of ISPs require you to use a forwarder to minimize the DNS traffic. You can simply define a forwarder using ucr, I use Google on IPv4 for the example
ucr set dns/forwarder1='8.8.8.8'
The other scenario might be a slow forwarder. To check it try to query the forwarder directly using the following command
dig univention.com #(ucr get dns/forwarder1)
If it takes long, then there is nothing the UCS server can do, you'll simply have to choose a different forwarder from the ucr command above.
If neither of the above helps, the next step would be to check whether there are error messages for the named daemon in the syslog file. Normally these come when you are trying to manually remove software or if the firewall configuration got changed.
Kevin
Sponsored post, as I work for Univention North America, Inc.
I re pointed my domain and it works for other people on both their PC and mobile, however when I try to load it on my local connection/wifi, it just loads a page with the words "OK." I suppose all I can do is wait, but not sure what the problem is.
When you say others, are they on the same network as you?
Have you tried flushing the DNS on your computer?
There may be a couple of factors at play, can we have a little more info.
If this is affecting all computers within your organisation it may be the site has the same name as the domain and the DNS server needs to be manually updated to point to an external website. It may also be that the DNS records has stale records, to manually delete these you have to open up DNS in the advanced view.
If it is just your PC and every other PC in the building can access is you may need to flush your DNS ( Windows Key + R, Type 'cmd' and then hit enter, then type ipconfig /flushdns and hit enter ).
Some routers keep an internal DNS cache, you can normally flush this by restarting the router.
Finally, there may just be a delay in the DNS records propogating globally, you can check the progress using tools like https://www.whatsmydns.net/
Sorry if this is a bit of a newbie question, but I am quite new to VPS and the relatively more complicated set up. I have a VPS set up, and every day or twice a day the site loads for a bout 10 minutes with no luck. Then when it comes back on line its fine after that. Upon logging on to Plesk, the server is up and running, very low CPU usage (0.10 and drops to 0.00 after a few minutes) and around 18% RAM usage.
The MySQLAdmin loads up fine.
So it seems the VPS is running fine.
Is there maybe another reason? The domain is with Daily.co.uk and the VPS is with LCN.com. Could there be another problem somewhere? On daily.co.uk, there are two nameservers set. ns0.etc*** and ns1.etc***. I did a tracert on windows cmd, this traced down to the server, with two timeouts.
I also tried a check on http://dnscheck.pingdom.com/ while the site was slow and this came back fine, except this: Too few IPv4 name servers (1). Only one IPv4 name server was found for the zone. You should always have at least two IPv4 name servers for a zone to be able to handle transient connectivity problems.
Any help would be appreciated. I have tried searching but with no luck.
The recommended diagnostic check for the issue you are experiencing is called a DIG.
On your Windows system, this check is not intrinsically available, but it can be downloaded from http://members.shaw.ca/nicholas.fong/dig/
Once you have installed it, you'll want to run it from the command prompt with the following syntax:
C:> dig -insert your domain here- +trace
This will show you how DNS resolution is happening from your location to the requested end point. Chances are, the error you received is correct. Most DNS setups have several name servers to assign to your domain registration to allow the round-robining of delegated name servers in the event that one becomes unresponsive.
My personal recommendation would be to outsource the DNS to a managed provider. Doing so will increase the availability of the zone, and reduce latency.
I have an issue that my idiot web host support team cannot solve, so here it is:
When I'm working on a site, and I'm uploading many files here and there (small files, most of them a few dozen lines at most, php and js files mostly, with some png and jpg files), after multiple uploads in a very short timeframe, the FTP chokes on me. It cuts me off with a "refused connection" error from the server end as if I am brute-force attacking the server, or trying to overload it. And then after 30 minutes or so it seems to work again.
I have a dedicated server with inmotion hosting (which I do NOT recommend, but that's another story - I have too many accounts to switch over), so I have access to all logs etc. if you want me to look.
Here's what I have as settings so far:
I have my own IP on the whitelist in the firewall.
FTP settings have maximum 2000 connections at a time (Which I am
nowhere near close to hitting - most of the accounts I manage
myself, without client access allowed)
Broken Compatibility ON
Idle time 15 mins
On regular port 21
regular FTP (not SFTP)
access to a sub-domain of a major domain
Anyhow this is very frustrating because I have to pause my web development work in the middle of an update. Restarting FTP on WHM doesn't seem to resolve it right away either - I just have to wait. However when I try to access the website directly through the browser, or use ping/traceroute commands to see if I can reach it, there's no problem - just the FTP is cut off.
The ftp server is configured for such a behavior. If you cannot change its configuration (or switch to another ftp server program on the server), you can't avoid that.
For example vsftpd has many such configuration switches.
Going to something else like scp or ssh should help
(I'm not sure that calling idiot your web support team can help you)
Is anyone aware of an easy way of duplicating and renaming a virtual PC (can be MS VPC, VMWare or Virtual Box), which is running SharePoint, K2 and acting as a domain controller? I’m looking for a method of creating an image which can be quickly and easily copied and run by multiple parties on the same network simultaneously without name conflicts. It’s either that or go through a ground-up build on each and every machine as far as I can see.
I'd advise against it.. renaming an installed SharePoint machine is sure to cause you pain indefinately and unexpectedly. The way to go is with scripted installs:
create copy of a VM with OS
rename machine + run sysprep
script install SQL
script install MOSS
script configure MOSS (replaces config wizard + a lot of manual settings)
It can all be done unattended.
As a shortcut to install short-lived development machines I have used the following. Just make sure the SharePoint configuration wizard runs after the rename and there should be no problem.
create a copy of a VM having: OS+SQL+MOSS(no config wiz)
rename machine
script configure MOSS
It has the advantage of your development machines being identically installed. Takes about 10 minutes to create a fresh one. It doesn't have sysprep but they are renamed so you can run them all on your network. Not running sysprep has never caused me grief but I wouldn't do it for production environments. Running the configuration of MOSS scripted makes sure it will work on the renamed environment (and all MOSS farms are configured exactly the same, same ports, SSP setup, etc, yay!)
For MOSS configuration scripting see h tt p://stsadm.blogspot.com/2008/03/sample-install-script.html
Plently of samples for SQL out there too.
SharePoint doesn't like having the server re-named from under it's feet (so to speak). Neither does SQL Server (which I assume you'd have installed on the VM for the installation). Not sure about a DC being renamed, there's probably problems there as well...
Having said that, there are some instructions I've read for renaming both SharePoint machines and SQL Server machines, so you might get somewhere.
On the third hand, I've tried it a few times and always ended up rebuilding the server from the ground up for SharePoint as it can get subtly mangled in ways which aren't always apparent straight away (the admin interface and shared services seem to be especially easy to confuse). I've found that I can build a vanilla MOSS install pretty quickly these days...
Sharepoint writes the name of the server into configuration tables in SQL Server. So if you change the name of the server, things stop working.
What you can do, is to install just the OS. Then take a copy each time you need a new machine. Run sysprep
to give the machine a new name. Then install SQL Server and MOSS.
This is not exactly what you are after but it should save you some time.
I've done this, and it wasn't too bad.
Rename the SharePoint-server first, then rename the Windows server.
This posting has a nice checklist.
Don't forget to remove the NIC node from the settings file of the virtual machine, otherwise you get name collision due to duplicate MAC addresses. Here's a how-to.
I believe the solutions above are really good. But I would suggest an alternative ...
If this is a development virtual PC I would suggest that you do the following
Do not rename the server
Change the IP address to be on different network
Change the MAC address so that there are no packet collisions
Since you are using it as a development VPC, edit the computer's lmhosts file edit the entry to point to the new IP address
You might want to skip the step 2 and be on the same network. But changing the hosts file will still point back to you. For example you server name was "myserver" and it was pointed 192.168.1.100 which was the local ip (has hosts file entry) , then if you copy the server give it ip 192.168.1.150 and edit the hosts file and point myserver to 192.168.1.150, the system will still work flawlessly. There will some domain name collisions in the event log of the machine, but it wont affect your development.