Task 6Managing IP Addresses by Using DNS
How to Create a Reverse DNS Zone
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Basic Dial NMS Implementation Guide
How to Create a Reverse DNS Zone
By creating reverse lookup zones for each IP subnet, you gain a robust database that can be used to track
assignments within an IP address space. Reverse lookups can determine the allocation status of any
address from any DNS client.
Network operators must account for used and unused IP addresses. It is recommended that each IP
address be given a DNS PTR Resource Record, even if the address is unused. For example, you can look
up and resolve an IP address as “unused-XXX.the.net.”
See the following example to create a zone from a BIND file by entering the zone command:
nrcmd> zone 101.21.172.in-addr.arpa. create primary file=the.net_rev_zone.txt
The following edited BIND definition file is for “the.net_rev_zone.txt.”
@ IN SOA onionring.the.net
esupport-austin.the.net. (
2000071600 ; serial number
3600 ; Refresh 1 hours
1800 ; Retry 30 minutes
86400 ; Expire 24 hours
86400 ; TTL 24 hours
)
;
IN NS onionring.the.net.
;
0 IN PTR broadcast-0.the.net.
1 IN PTR unused-1.the.net.
2 IN PTR unused-2.the.net.
3 IN PTR unused-3.the.net.
4 IN PTR unused-4.the.net.
5 IN PTR unused-5.the.net.
6 IN PTR unused-6.the.net.
7 IN PTR unused-7.the.net.
8 IN PTR unused-8.the.net.
9 IN PTR unused-9.the.net.
10 IN PTR unused-10.the.net.
11 IN PTR unused-11.the.net.
12 IN PTR unused-12.the.net.
13 IN PTR unused-13.the.net.
14 IN PTR unused-14.the.net.
15 IN PTR unused-15.the.net.
16 IN PTR unused-16.the.net.
17 IN PTR unused-17.the.net.
18 IN PTR unused-18.the.net.
19 IN PTR unused-19.the.net.
20 IN PTR doc-rtr58-01.the.net.
21 IN PTR doc-rtr54-01.the.net.
22 IN PTR doc-rtr53-01.the.net.
23 IN PTR doc-rtr53-01.the.net.
(Truncated for brevity..)
253 IN PTR unused-253.the.net.
254 IN PTR unused-254.the.net.
255 IN PTR broadcast-255.the.net.
For a sample BIND file that can be used as a template and edited for your environment, go to
http://www.cisco.com/univercd/cc/td/doc/cisintwk/intsolns/dialnms/bindtemp.txt