network_cmds-480.tar.gz

[apple/network_cmds.git] / unbound / libunbound / python / doc / examples / example1b.rst

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+.. _example_reverse_lookup:
+
+==============================
+Reverse DNS lookup
+==============================
+
+Reverse DNS lookup involves determining the hostname associated with a given IP address.
+This example shows how reverse lookup can be done using unbound module.
+
+For the reverse DNS records, the special domain in-addr.arpa is reserved. 
+For example, a host name for the IP address 74.125.43.147 can be obtained by issuing a DNS query for the PTR record for address 147.43.125.74.in-addr.arpa.
+
+::
+
+       #!/usr/bin/python
+       import unbound
+       
+       ctx = unbound.ub_ctx()
+       ctx.resolvconf("/etc/resolv.conf")
+       
+       status, result = ctx.resolve(unbound.reverse("74.125.43.147") + ".in-addr.arpa.", unbound.RR_TYPE_PTR, unbound.RR_CLASS_IN)
+       if status == 0 and result.havedata:
+               print "Result.data:", result.data.domain_list
+       elif status != 0:
+               print "Resolve error:", unbound.ub_strerror(status)
+
+In order to simplify the python code, unbound module contains function which reverses the hostname components. 
+This function is defined as follows::
+
+       def reverse(domain):
+               return '.'.join([a for a in domain.split(".")][::-1])
+
+