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Re: [nv-l] DNS or hosts file resolution

To: nv-l@lists.us.ibm.com
Subject: Re: [nv-l] DNS or hosts file resolution
From: Jane Curry <jane.curry@skills-1st.co.uk>
Date: Thu, 28 Oct 2004 22:00:42 +0100
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I have the same comments as Paul and Ray. Use DNS. Setup a secondary DNS server on the NetView system. Be religious about ensuring that address-to-name resolutions exist and are accurate. If your systems have loopback addresses, then that's the single entry that you put in the forward files and that's the entry you put into NetView's netmon.seed if you need to. Check the nv-l archive for more instructions ( http://lists.skills-1st.co.uk/mharc/html/nv-l/ ) on this subject.

Incidentally, I normally setup a non-DNS SmartSet that catches any hosts that NetView finds that isn't in the DNS. If you have dome the 5-day NetView class, you will have seen this. It's a horrible regular expression to type correctly but you basically create a SmartSet of nodes whose hostname field is an IP address. The expression you want is (I hope):
 ~   ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$

That is:
~ denotes a regular expression rather than an exact match. You select this from a box selection in the SmartSet editor.
^ denotes the start of the line
[0-9] denotes the characters 0 through 9
{1,3} denotes the previous field between 1 and 3 times ie values strictly between 0 and 999 - not quite good enough to match strict IP addresses but probably close enough. The "." in the IP address you have to escape with a "\" as otherwise "." matches any character
..... all that 4 times over
$ denotes the end of the expression

You can use nvUtil l <smartset name> to print out a list of the members of the non-DNS SmartSet and send it to whoever maintains your master DNS.

I'm sure Don Davis, the king of regular expressions for SmartSets, will put me right if I've got this wrong! I will also add this entry to the NetView Tivoli User Group site under Hints and Tips, Config Mgmt.

Cheers,
Jane

Federico Vidal wrote:

Hello:
Does anyone has an idea or rule to follow when deciding how to resolve names with Netview? I'm aware that Netview extensively uses name resoltion, especially with large databases. This will affect DNS server performance if it is not a dedicated server. Also I'm aware that very long /etc/hosts can cause Netview delays. This option is also trickier because it is another thing to maintain besides de DNS. Both scopes have advantages and disadvantages. My questions to the list are: Is there a guideline or rule to follow when deciding when to use or not use the corporate DNS server?
How large has to be the /etc/hosts file to hinder Netview's performance?
What is the impact of Neview to the DNS server?
Best Regards and thanks, Federico Vidal


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