CODEWITHSUNDEEP
javadnsinetaddress
zJK
zJK

Reputation: 151

DNS query in Java

I am messing around with DNS services in Java. I am specifically trying to look up all google.com addresses and display them in an array, similar to running a lookup using nslookup:

nslookup -q=TXT _netblocks.google.com 8.8.8.8

I am using InetAddress for this but I keep on getting exceptions. Since the exceptions refer to an 'Unknown Host', I don't think InetAddress can read TXT records (if I use google.com it works, but that doesn't show the full IP range).

Below is my code:

InetAddress dnsresult[] = InetAddress.getAllByName("_netblocks.google.com");

for (int i=0; i<dnsresult.length; i++)
    System.out.println(dnsresult[i]);

I would appreciate it if someone could point me in the right direction.

Upvotes: 15

Views: 37787

Answers (4)

Jasper de Vries
Jasper de Vries

Reputation: 20263

I ended up using Google's "JSON API for DNS over HTTPS (DoH)"

https://developers.google.com/speed/public-dns/docs/doh/json

Upvotes: 1

user988346
user988346

Reputation: 1888

Here is an example that does what you are trying to do:

Attribute attr = new InitialDirContext().getAttributes("dns:_netblocks.google.com", new String[] {"TXT"}).get("TXT");
System.out.println("attr.get() = " + attr.get());
System.out.println("attr.getAll() = " + Collections.list(attr.getAll()));

If you want to use a custom dns server use "dns://1.1/_netblocks.google.com" instead.

Upvotes: 7

user207421
user207421

Reputation: 311054

InetAddress doesn't do this, but you can accomplish DNS TXT record lookups in Java via the JNDI DNS provider.

Upvotes: 5

Manish Maheshwari
Manish Maheshwari

Reputation: 4134

You cannot lookup TXT or other DNS records InetAddress class. InetAddress.getAllByName() looks up for A, or AAAA records only.

Check DNS Java for your needs.

Upvotes: 12

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