DNS Round Robin.

[SmittyNMCI]

A question that I hope someone can help with.

I am running w2k print servers and have implemented a dns round robin with A records.

Ex. PrintServer A x.x.x.1
PrintServer A x.x.x.2

The round robin works great when I ping the virtual name "PrintServer", when I TS into the virtual "PrintServer" or when I nslookup into the virtual "PrintServer". However, when I use Start, Run and \\PrintServer, I get a duplicate name exists on the network error. To do what I need to do, I really need to use the Start, Run, \\PrintServer in order to map to printers and I need to go to the virtual "PrintServer" to do it or the round robin will not work.

Anyone with ideas on why the error and the fix or maybe another way to map to the printers I would appreciate it.

 

[ProfFate]

If you are trying to use Round Robin to load balance Win2k print servers, I really don't think it will work. Maybe you should tell us what you are trying accomplish, because there might be another solution.

MikeL

 

[SmittyNMCI]

The print servers on the network are currently clustered so load balancing is a concern but the largest concern is redundancy. The management has decided that clustering has proven disasterous and so we will break all the clusters.

The current solution for redundancy is to have the same server pair hold half the original queues and when one member of the pair fails, to migrate the half the failed server holds to the surviving node then delete the DNS/WINS entries, wait for replication (set to 1 hr) then enter a CNAME to point the failed nodes name to the surviving node. This unfortunately forces us into a failed SLA (Service Level Agreement) situation which costs us money.

My idea was to join the two servers into a DNS Round Robin using DNS A records and put all of the queues on both nodes. This would allow a simple and fast removal of the failed node from the DNS Round Robin entry and keep us out of the failed SLA.

The network needs to be able to perform this solution with minimal impact on the customers and with no additional costs so a third party solution is out of the question. Round Robin also gave the added benefit of static load balancing which would be nice but is second on the list.

The Round Robin solution worked great and the servers were accessed in order as it should be but because the queues cannot be published to the domain (by order of the engineers and management) the only way to attach clients to printers is to \\ into the virtual A record name then connect to the printer required. This is where the Round Robin fails. \\ returns a duplicate name error even though the Round Robin works in every other instance needed.

The reason for this, I believe, is that the \\ method uses netbios naming convention and DNS automatically enters both A record entries into the netbios convention causing dup name errors.

So my question is most likely this. Can netbios be disabled for this application without disrupting the other netbios requirements in place on the network or is there indeed another solution that would work that would not require expenditure, not have an impact on security or client access and still provide redundancy?

 

[SmittyNMCI]

Has anyone ever heard of a bug in Windows 2000 concerning duplicate name errors when using netbios name callup? The following web site

http://www.cytex.com/Access/Microsoft/CIFS/w2ks_duplicate_name_bug.htm

talks about this problem. Anyone have any thoughts on this?

Smitty
A+ Network+ MCSA MCSE

 

[ProfFate]

Yes, I've had the duplicate name problem before. I have many servers that have two NICs, one for the main network and one for a network where I do all of my backups. My main NIC has a DNS entry that is the name of the server. The NIC for my backup network has different DNS entry, for that IP address. The problem you described was fixed in SP3 and requires a Registry edit. Here is the Q-article from MS that describes the issue. This might help you with your printer shares, but I still think Round Robin isn't going to work in your case. Good luck.

http://support.microsoft.com/default.aspx?scid=kb;en-us;281308

MikeL

 

[SmittyNMCI]

Yes indeed. I need to look at this article more closely. The article that I entered above states that MS says that they fixed the bug in sp3 however the article further states that the fix that MS provided in sp3 did not work. Any thoughts on this? Also, could you explain why you feel that round robin will not work in my case.

Jeffery Smith (Smitty)
PEC Solutions Inc.
A+ Network+ MCSA MCSE

 

[ProfFate]

This patch and registry setting fixed my duplicate name problem. If it doesn't work for you, you might have a different issue.

I've never tried using round robin for print server load balancing, it's just a gut feeling. The idea of connecting to a "physical" share that can connect to a different server at any given time, but just doesn't sound good in a Windows environment. I printer share is a lot different than something like a web site, where you might use load balancing. I have setup clustered print servers, using MS's cluster technology. That works, but as I think you stated it can be flakey at times.

This is what I did at a place I used to work at. I built two print servers. One was the production server and one was a backup server. Each night or once a week I would backup all of the printer shares, drivers, and ports on the production print server. If the production print server every failed, I would restore the backup to the backup print server, and then rename it. I never had to do this, but in my tests it would take me about 15 minutes to bring the other server on-line. I'm not sure if this is fast enough for you, but it worked for us.

Here is a very nice tool to use to backup your printer information and restore it to a different server.

http://www.microsoft.com/downloads/...familyid=d6915f13-ede4-4708-83c1-0091eeade293

MikeL

 

[SmittyNMCI]

The hotfix for Q281308 fixed my dup name problem. Now I can \\ into the servers using the virtual name. Added a static WINS entry for the virtual name to be able to call up the servers without having to use the FQDN. All that now works. Round Robin is functioning as expected HOWEVER, (big pause on this comma) when I \\ into the virtual server name, I see the list of printers just fine but when I try and connect to a printer an error is generated that states the printer name is bad or the printer has been disconnected from the server. When I \\ into the actual name of the server and see the list of printers I can map to a printer just fine so the name is correct and it is still connected to the server. This just gets stranger and stranger.

I also use PrintMigrator to back up all of the print servers but because we administer to remote sites all over the country, the connection is rather slow even though we are using t-3 lines so transfering huge 50-60 meg files to the server is slow at best and your 15 minutes turns into 45 minutes for us. This is deffinately not fast enough. Will keep plugging away at a solution though.

Jeffery Smith (Smitty)
PEC Solutions Inc.
A+ Network+ MCSA MCSE

 

[ProfFate]

As for the PrintMigrator software. I set up a batch file that would run each night. As one of the parameters of the PrinMigrator, I would redirect the output to a hard drive on the "backup" print server. That way the file is already there. You could then use Terminal Server or remote control your server in some way. We use Compaq/HP servers, so we use LightsOut boards to remote administer our servers, or we use IP enabled KVMs. Good with everything.

MikeL

 

[compgirlfhredi]

Have you tried this?

DNSLint is a command-line Microsoft utility designed to help you diagnose common DNS name resolution issues. DNSLint can be downloaded from the Microsoft Download Center. DNSLint has three functions that verify Domain Name System (DNS) records and generate an HTML report. The three functions are:
dnslint /d: This diagnoses potential causes of "lame delegation" and other related DNS problems.
dnslint /ql: This verifies a user-defined set of DNS records on multiple DNS servers.
dnslint /ad: This verifies DNS records specifically used for Active Directory replication.
DNSLint syntax is:
dnslint /d domain_name | /ad [LDAP_IP_address] | /ql input_file
[/c [smtp,pop,imap]] [/no_open] [/r report_name]
[/t] [/test_tcp] [/s DNS_IP_address] [/v] [/y]

http://download.microsoft.com/download/win2000srv/Utility/Q321045/NT5XP/EN-US/dnslint.exe

Right now, you occupy a point where three lines reach across the expanse of time and space and intersect only there, and that you and only you possess.