dnsjava-users

DNS Resolve from hosts file first then DNS Server

[Saran1 <har...@re...>]

Hi,

I want to resolve the DNS names for the internal and external IPAddresses
using Java and DNSJava. Below java code resolve the names from 'hosts' file
first and then contact the DNS Server for resolution.

System.setProperty("sun.net.spi.nameservice.provider.1","dns,dnsjava");
InetAddress addr = InetAddress.getByName(ipaddress);
String dnsname = addr.getCanonicalHostName().trim();
System.out.println("DNS...........:" + dnsname);

But after setting the "dnsjava-2.0.3.jar" in classpath, the above code
doesn't look my 'hosts' file. Please let me know for any reason behind the
same.

My Requirement:
1. Faster the DNS Resolve [using dnsjava.jar]
2. First look for 'hosts' file, then contact DNS Server.

Please help me to solve the problem. Any help will be highly appreciated.

Thanks.
Saravanan 
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Re: DNS Resolve from hosts file first then DNS Server

[Brian W. <bwe...@xb...>]

On Tue, 12 Feb 2008, Saran1 wrote:

> I want to resolve the DNS names for the internal and external IPAddresses
> using Java and DNSJava. Below java code resolve the names from 'hosts' file
> first and then contact the DNS Server for resolution.
>
> System.setProperty("sun.net.spi.nameservice.provider.1","dns,dnsjava");
> InetAddress addr = InetAddress.getByName(ipaddress);
> String dnsname = addr.getCanonicalHostName().trim();
> System.out.println("DNS...........:" + dnsname);
>
> But after setting the "dnsjava-2.0.3.jar" in classpath, the above code
> doesn't look my 'hosts' file. Please let me know for any reason behind the
> same.

Because dnsjava is a library implementing the DNS protocol, and /etc/hosts 
is not part of the DNS protocol.

> My Requirement:
> 1. Faster the DNS Resolve [using dnsjava.jar]
> 2. First look for 'hosts' file, then contact DNS Server.
>
> Please help me to solve the problem. Any help will be highly appreciated.

You have several options:

1) Do the /etc/hosts lookup yourself.
2) Find or create a patch to dnsjava which implements /etc/hosts file 
lookups, and submit it.

Brian