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Two nameservers needed

Posted on 2001-06-20
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Last Modified: 2010-04-17
I have two nameservers that I need to access on my machines.  I want to access the primary one first, and if it can't resolve the name, use the secondary nameserver.  I don't want to EVER use the secondary server unless the name can't be resolved through the primary server.  The way I think the nameservers work is that they only access the secondary server if the primary times out, so if the primary server is alive, the secondary server will never be accessed (which isn't what I want).  Is there a way for me to configure my machines to try the primary server, then if the name isn't found, try the secondary server?  I'm running WinNT, Win2K, & Solaris 7.
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Question by:wysecj
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13 Comments
 
LVL 1

Expert Comment

by:Haho
ID: 6212670
yes, you are correct. If the primary times out, then it will go to the secondary DNS server to query the name.

May be what you can do is to in your case is to have two primary servers? A simple script can be written to "sync" both primary servers...

Cheers
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LVL 17

Expert Comment

by:mikecr
ID: 6215386
Well, there's a little snag with that, if you have two nameserver addresses listed and it does contact the first one, but it's busy, it will notify your WINS and it will use the second one. I would put an LMHOSTS file on your computer with the name mapping in it of the Primary and put the secondary address as the nameserver address in the TCP/IP properties. This way it will always look at the static entry first (this is by design) then to go what you have supplied in TCP/IP as the secondary.
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Author Comment

by:wysecj
ID: 6216979
Haho,

I'm not sure what kind of script I would write.  One server serves names in the 147.11.0.0 subnet, the other one is for the rest of the internet.  The servers should never be "sync'd" (i.e. - identical).  Also, the nameservers are not on my network, so I don't have control of them.

Mikecr,
I need an example of what you want me to put in the LMHOSTS file, and how you think the TCP/IP DNS properties should be defined.  Does LMHOSTS allow you to specify a nameserver, or is it just like the unix hosts file?  Even if I specify a nameserver in LMHOSTS, why would it act any different, other than getting the first name server from LMHOSTS and the second from the DNS properties.  Also, what about a solution for Solaris?
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Author Comment

by:wysecj
ID: 6216983
Haho,

I'm not sure what kind of script I would write.  One server serves names in the 147.11.0.0 subnet, the other one is for the rest of the internet.  The servers should never be "sync'd" (i.e. - identical).  Also, the nameservers are not on my network, so I don't have control of them.

Mikecr,
I need an example of what you want me to put in the LMHOSTS file, and how you think the TCP/IP DNS properties should be defined.  Does LMHOSTS allow you to specify a nameserver, or is it just like the unix hosts file?  Even if I specify a nameserver in LMHOSTS, why would it act any different, other than getting the first name server from LMHOSTS and the second from the DNS properties.  Also, what about a solution for Solaris?
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Author Comment

by:wysecj
ID: 6216984
Sorry about the duplicate post.
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LVL 17

Expert Comment

by:mikecr
ID: 6217934
The first things Windows computers look at during name resolution is the static files on their drives. You have two types of name servers, WINS (Windows internet naming service) which maps a computer name to an IP address and DNS which does basically the same thing except it uses the domain name. If you edit the Hosts file you'll put in a line similar to:
10.1.1.1      Mycomputer

Which means that the IP address for mycomputer is 10.1.1.1 which helps with the name resolution. WINS works the same way. There are hosts files and a lmhosts.sam template located on every Windows computer. You said that you wanted to force name resolution and this is how you would do it. When relsoving the name it will use the static hosts and lmhosts files first before looking into the tcp/ip settings for it. But remember like I said above, this may not happen 100 percent of the time. If the nameserver is busy it may pass you off to another one to do the name resolution.
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Author Comment

by:wysecj
ID: 6220674
Mikecr,

The hosts file isn't going to help me use two nameservers.  Also, I don't know all the names on the 147.11.0.0 subnet, so I can't put them in the hosts file.  Even if I could, they are constantly adding and deleting machines.  I want to use the two nameservers to resolve the names - I don't want to have to create a hosts file on each machine on my network, that my be out of date.  If I'm missing something, let me know.
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LVL 3

Expert Comment

by:moorthy_kulumani
ID: 6223216
hi,
 
  managing HOSTS file is very big headache.In your case i think no need to confuse with WINS too.
  13 root servers r there from A to M.your  DNS have to access root server  for resolving any host name to IP that ur DNS is not having in cache.
  As per I know U R request is not possible.consider U r primary is PDNS and secondary SDNS.all ur clients have both entries.
 when ur clients want some hostname-ip it will ask for PDNS then PDNS will  look it own cache if that is not there it will go to ROOT server to resolve ur clients query.so all work has to done by primary DNS.exmp. suppose ur putting SUPPORT.COMPAQ.COM it is not in ur PDNS cache it will contact root server and make a note of (1)COMPAQ.COM zone DNS servers ip (2)A record of SUPORT ip address in cache.
now ur putting some other say www.compaq.com it will look in to cache and it is not having www record query for compaq.com but it is having DNS servers ip of compaq.com then  it will ask directly the DNS of COMPAQ.com and get the result of WWW record.
 
    UR PDNS and SDNS sync will happen depends in setting
that what ur having.(both sol and NT).so sync factor u have to optimise.
  since the process is like this if ur SDNS will be knowing nothing when the PDNS in picture.obviously it will get from PDNS only.
  So my option is make the Primary DNS on good wire.(good BW and it shd be good conf.(HW)).
we r implementing ISPs i have never come  across  u r query from any one.if u have clear with DNS works  u will come to know why for secondary dns.

  bye
moorthy
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Author Comment

by:wysecj
ID: 6224897
Moorthy,

I had a little trouble understanding your response, but I think the gist of it is that you don't think it can be done.  

Here's a little more clarification:

1.  I understand the reason for a secondary DNS.  If the first one is down, the second one takes over.  I'm wondering if there is a way for me to modify the configuration on my machines such that if the first one can't resolve the name, the second one takes over.

2.  The reason I want to do this is to minimize ISDN line usage but still provide complete name resolution.  My ISDN line connects to my company in California from CT, at $0.15/minute.  In addition to being much slower than my cable modem, the charges for the ISDN add up.  In addition to an ISDN line, I have a cable modem.  The cable access is a fixed charge, and much quicker.  Therefore, I'd like to use the cable modem to access the name server UNLESS I need internal access to my company.  In that case, I'll need to go through the name server on the ISDN line.  If I make the ISDN name server the primary, I'll be dialing CA every time I need to resolve a name.  Hope this clarifies the situation a little better and my reason for wanting this.

3.  I'm open to setting up a name server on either my SUN or Win2K platform.  However, I'm not familiar with this, and need some guidance.  Specifically, how do I set it up to minimize the ISDN access?  I high level description of the steps to configure it properly, and what software to use.  
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Accepted Solution

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moorthy_kulumani earned 200 total points
ID: 6226244


 You want to use cable Line as much as possible when u dont need internal access to company.

 how many clients(machines) ur having ?

 where ur primary DNS is sitting thru ISDN line ?
 
 where ur secondary DNS is sitting thru cable ?

 which DNS ur able to get within 30 ms.?
 
 Those DNS are owend by  ur company or cable line     Provider  or any ISP 's DNS server.?
 
 can u install DNS cache only in ur network ?
 
first of all u shd know the If primary is not resolving names the secondary will resolve without fail.it is not depend on that .it is depend on how ur access time to the DNS servers and how fast query resolved thru each DNS.by accessing ROOT server or whatever.
 
 if ur able to get any DNS server within 30 ms that is fine.that will resolve ut quries.u can configure the best server as a primary.

 Or you can install CACHE ONLY DNS on win2k or solaris.
Solaris 8 means it is easy coz of GUI.otherwise u have to go thru EDITING some 8 files and all u have to do.

 SO better u can Install win2k server as a CACHE ONLY DNS server. It is quit easy .just few clicks away.

 if u want i will tell u how to install CACHE ONLY DNS ON WIN2k.

 all the best.



 
 moorthy
 


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Author Comment

by:wysecj
ID: 6226346
Moorthy,

Here are your answers/comments, one for each paragraph:

1.  3 clients -  1 Solaris, 1 WinNT, 1 Win2K
2.  Primary DNS is currently through ISDN
3.  Secondary DNS is through cable modem
4.  Cable modem DNS connects quickly,  ISDN usually needs to dial-up (disconnects after 45 seconds of idle time)
5.  The ISDN DNS is owned by my company.  Cable DNS is from ISP.
6.  Could install DNS cache on my network, but I don't know what software is required or how to configure it.
7.  Your answer explains a lot.  I have trouble resolving internal (ISDN) addresses sometimes.  It must use the cable DNS whenever the ISDN needs to dial.
8.  I can always get a connection within 30 ms, but I can't always avoid the phone call to CA.  I only want to make the phone call for internal addresses.  Also, if I make the cable DNS primary, I can NEVER resolve any internal names.
9.  Cache only DNS sounds like what I want.  Do you have some more details on what to install?  
10. A few clicks would work for me.
11. Please divulge.

Thanks for your help.  I think the cache only DNS will do the job.  
0
 

Author Comment

by:wysecj
ID: 6226396
One more bit of info.  I'm running Win2K Workstation, not server.  I could install the DNS on either WinNT or Solaris.  
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Author Comment

by:wysecj
ID: 6376405
Moorthy provided a lot of help, although my final question was never answered.
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