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Old 10-04-2004, 09:53 AM   #1
emailssent
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(nslookup) vs (dig and host)


Why nslookup has been going to depricated and dig and host has been introduced.

what is advantages?
 
Old 10-04-2004, 12:22 PM   #2
scowles
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I have no idea why the Bind developers are deprecating nslookup, but I'd be willing to bet is has to do with the development team no longer having resources to support code that is older than dirt (so to speak).

BTW: For the most part, the dig and host commands basically output the same info. They just have different defaults. Example:

dig +short www.yahoo.com
host www.yahoo.com

will basically print the same output. The host command is a little more descriptive.

While the inverse of the above

dig www.yahoo.com
host -d www.yahoo.com

basically prints the same output. The dig command includes some timing stats and the actual query that will be performed.

Just for grins, try:
nslookup -debug www.yahoo.com

Although the output is in a different format, the information that is printed out is basically the same as dig.

If you want the full enchilada...

nslookup -d2 www.yahoo.com
...or
dig -d2 www.yahoo.com
 
Old 10-05-2004, 12:27 AM   #3
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thanks,

thanx,

and where should we configure the cachening only server?
 
Old 10-05-2004, 01:45 AM   #4
darthtux
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In the named.conf file
http://langfeldt.net/DNS-HOWTO/BIND-9/DNS-HOWTO-3.html
 
Old 10-05-2004, 07:01 AM   #5
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thanks,
 
Old 10-05-2004, 09:18 AM   #6
scowles
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emailssent,

Just an FYI: The DNS server that you configured earlier is a "caching" name server. The only difference between what you have currently configured and a "caching only" name server is your configuration loads a couple of authoritative zones for your private network (which is good). But it still caches all non-authoritavie queries just like a "caching ony" configuration would. So the configuration you setup earlier is actually better.
 
Old 10-05-2004, 11:44 PM   #7
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Hi Scowles,


Plz. tell me what is FYI

In my first post of thread

http://www.linuxquestions.org/questi...hreadid=233679

i just configured a caching only server becz at that time i couldn't make a difference between master , slave and caching.

Now, i think either its master or slave it will also be caching server
if contains

#/etc/named.conf
options {
directory "/var/named";
{;

zone "." {
type hint;
file "root.hints";
};

zone "0.0.127.in-addr.arpa" {
type master;
file "named/127.0.0";
};

AM i right or not plz. clarify.
Quote:
So the configuration you setup earlier is actually better.
And plz. tell what is the meaning of above line, means how earlier configuration is better



--jack
 
Old 10-06-2004, 08:38 AM   #8
scowles
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Quote:
Plz. tell me what is FYI
FYI = For Your Information

Quote:
i just configured a caching only server becz at that time i couldn't make a difference between master , slave and caching.
snip...

AM i right or not plz. clarify.
Technically, a caching-only server does not load any authoritaive zones, just the root (hint) and localhost reverse zones. In short, a caching-only server caches (stores in RAM) all queries that its asked to resolve by clients configured to use this server. It's not authoritative for anything.

So by definition, the DNS server you configured in the other thread is no longer a caching-only DNS server. Why? Because it now loads a couple of authoritative zones for your private network. But it still caches all non authoritative queries just like a "caching-only" server would, but it also answers authoritaive queries for your private domain. Which is good!

With reagrds to the master/slave designation - The terms master/slave are only meaningful among the configured DNS servers. i.e. I'm not aware of a RR type that returns a master/slave designation. A DNS server configured to load a zone as a slave will transfer its authoritative copy of that zone from the DNS server that loads the same zone name as a master. But heres the kicker (and the source of confusion for people learning DNS)... DNS servers use a round-robin algorithm during a query that involves recursion. So if your domain name lists two name servers as authoritative (one master, one slave) a remote DNS server (like mine) will alternate queries between the two name servers to fetch answers. It will not query the so called master name server first (everytime), and if no answer is received (server down), query the slave. In fact, ISP's like yahoo, use this round-robin algorithm to distribute bandwidth among multiple servers. Checkout how many servers are listed for www.yahoo.com

If you want to visually see round-robin in effect, try using dig +trace for the same domain name multiple times and watch where the responses are received from. Especially from the TLD name servers.

BTW: When you are ready to test your DNS server (should you register your domain) , checkout: www.dnsstuff.com
 
  


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