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List:       maradns-list
Subject:    Re: Doubt
From:       Sam Trenholme <sam+i7tq5rg () chaosring ! org>
Date:       2005-07-09 22:18:43
Message-ID: f0f3e078066c-2005-jul-09.15.08 () samiam ! org
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>How do I set up reverse DNS on MaraDNS?

You may have an older version of MaraDNS with an out of date FAQ.  Here
is the current FAQ entry:

	By using PTR (pointer) records. For example, the PTR record which
	performs the reverse DNS lookup for the ip 1.2.3.4 looks like this
	in a CSV1 zone file:

    		P4.3.2.1.in-addr.arpa.|86400|www.example.com. 

	If you wish to have a PTR (reverse DNS lookup; getting a DNS name
	from a numeric IP) record work on the internet at large, it is not a
	simple matter of just adding a record like this to a MaraDNS
	zonefile. One also needs control of the appropriate in-addr.arpa.
	domain.
	
	While it can make logical sense to contact the IP 10.11.12.13 when
	trying to get the reverse DNS lookup (fully qualified domain name)
	for a given IP, DNS servers don't do this. DNS server, instead,
	contact the root DNS servers for a given in-addr.arpa name to get
	the reverse DNS lookup, just like they do with any other record
	type.

	When an internet service provider is given a block of IPs, they are
	also given control of the DNS zones which allow them to control
	reverse DNS lookups for those IPs. While it is possible to obtain a
	domain and run a DNS server without the knowledge or intervention of
	an ISP, being able to control reverse DNS loookups for those IPs
	requires ISP intervention.

If this doesn't answer your question, let us know.

/etc/resolv.conf affects which recursive DNS server is used to look up
hosts on the internet.  It looks like this when MaraDNS is acting as
a recursive nameserver on the ip 127.0.0.3:

----8<----8<----8<----8<----8<----
nameserver 127.0.0.3
----8<----8<----8<----8<----8<----

/etc/hosts determines the host names which one does not want to resolve via
DNS.  It looks something like this:

----8<----8<----8<----8<----8<----
127.0.0.1 ad.doubleclick.net
127.0.0.1 ad.yieldmanager.com
----8<----8<----8<----8<----8<----

In this example, we have these sites, which are used to display banner ads,
resolve to 127.0.0.1 so we don't have to see ads from these sites.  (As it
turns out, this is not how I get around ads; I use click-to-flash and don't
allow animated gifs to loop)

I hope this helps?

- Sam

P.S.  How do I tell one of my pretty Brazilian friends they they are a
beautiful girl in Portuguese?

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