IN-ADDR.ARPA
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... IP address to host name support. The existing support is
the IN-ADDR.ARPA section of the DNS name space. As a result this RFC
describes one structure for network ...
... create network number to name
entries in IN-ADDR.ARPA domains under his control. Thus, the name
for the ARPANET ...
... The same network number slots already assigned and delegated
in the IN-ADDR.ARPA section of the name space. ...
... space is overwhelming and would lead to the WKS syndrome. (As
of February, 1989, approximately 400 sections of the
IN-ADDR.ARPA tree are already delegated, usually at network
...
... method is used for subnets in a nested
fashion. For example, 0.0.0.10.IN-ADDR.ARPA. for net 10.
...
...
0.0.2.128.IN-ADDR.ARPA. PTR cmu-net.cmu.edu.
A 255.255.255.0
...
...
In general, this information will be added to an existing
master file for some IN-ADDR.ARPA domain for each network
...
...
isi-net.isi.edu. PTR 0.0.9.128.IN-ADDR.ARPA.
...
... domain name of the organization; this is a
different file from that which holds the information below
IN-ADDR.ARPA. Similar PTR RRs can be used at subnet names.
...
... The data here is one or more PTR RRs pointing at the
IN-ADDR.ARPA names corresponding to host-zero entries for
networks ...
...
ISI.EDU. PTR 0.0.9.128.IN-ADDR.ARPA.
MCC ...
... MCC.COM. PTR 0.167.5.192.IN-ADDR.ARPA.
PTR 0.168.5.192.IN-ADDR.ARPA.
PTR 0.169.5.192.IN-ADDR.ARPA.
...
... PTR 0.169.5.192.IN-ADDR.ARPA.
PTR 0.0.62.128.IN-ADDR.ARPA.
...
...
Note that all of the usual host and corresponding IN-ADDR.ARPA
entries would still be required.
...
... ; Define network entry
isi-net.isi.edu. PTR 0.0.9.128.IN-ADDR.ARPA.
; Define first level subnets ...
... subnets
div1-subnet.isi.edu. PTR 0.1.9.128.IN-ADDR.ARPA.
div2-subnet.isi.edu. PTR 0.2.9.128.IN-ADDR.ARPA ...
... IN-ADDR.ARPA.
div2-subnet.isi.edu. PTR 0.2.9.128.IN-ADDR.ARPA.
; Define second level subnets ...
... ; Define second level subnets
inc-subsubnet.isi.edu. PTR 16.2.9.128.IN-ADDR.ARPA.
in the 9.128.IN-ADDR.ARPA ...
... network number and address mask
0.0.9.128.IN-ADDR.ARPA. PTR isi-net.isi.edu.
A 255.255.255.0 ;aka X'FFFFFF00'
...
... ; Define one of the first level subnet numbers and masks
0.1.9.128.IN-ADDR.ARPA. PTR div1-subnet.isi.edu.
A 255.255.255.240 ;aka X'FFFFFFF0'
...
... ; Define another first level subnet number and mask
0.2.9.128.IN-ADDR.ARPA. PTR div2-subnet.isi.edu.
A 255.255.255.240 ;aka X'FFFFFFF0'
...
... ; Define second level subnet number
16.2.9.128.IN-ADDR.ARPA. PTR inc-subsubnet.isi.edu.
...
... high one, two, or three bytes, respectively. Reverse the octets,
suffix IN-ADDR.ARPA, and do a PTR query.
...
... get 10.0.0.0.
2. Construct the name 0.0.0.10.IN-ADDR.ARPA.
3. Do a PTR query ...
... and get 128.9.0.0.
2. Construct the name 0.0.9.128.IN-ADDR.ARPA.
3. Do a PTR query ...
...
1. As before construct a query for 0.0.9.128.IN-ADDR.ARPA.
Retrieve:
...
... Retrieve:
0.0.9.128.IN-ADDR.ARPA. PTR isi-net.isi.edu.
A 255.255.255.0
...
... (255.255.255.0), constructing a query for
0.2.9.128.IN-ADDR.ARPA. Retrieve:
0.2.9.128.IN-ADDR.ARPA ...
... 255.255.255.240 (x'FFFFFFF0'). constructing a query for
16.2.9.128.IN-ADDR.ARPA. Retrieve:
16.2.9.128.IN-ADDR.ARPA ...
... IN-ADDR.ARPA. Retrieve:
16.2.9.128.IN-ADDR.ARPA. PTR inc-subsubnet.isi.edu.
4. Since no A RR ...
...
Such a precomputed index is what we mean by YP, and we regard the
IN-ADDR.ARPA domain as the first instance of a YP in the DNS.
...
...
IN-ADDR.Netname.YP. PTR IN-ADDR.ARPA.
...