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Newbie asks for reverse IP lookup info

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Newbie asks for reverse IP lookup info DNS forum discussing issues, servers, and configurations. The Domain Name System (DNS) is what the Internet uses to translate website names into IP addresses.

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  #1  
Old September 27th, 2003, 02:39 AM
thegoods thegoods is offline
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Question Newbie asks for reverse IP lookup info
Example: If I do a reverse IP lookup for IP address 81.77.255.33, the result is user-1825.bbd24tcl.dsl.pol.co.uk. Can someone please explain to me what this means? Is the IP address the person's PC? If so, what is the "result"?

BTW, I'm using URL
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  #2  
Old September 27th, 2003, 10:40 AM
M.Hirsch M.Hirsch is offline
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Quote:
If I do a reverse IP lookup for IP address 81.77.255.33, the result is user-1825.bbd24tcl.dsl.pol.co.uk. Can someone please explain to me what this means?

Your ISP is assigning this name to you. But this looks like a kind of information leak to me: user-1825 is hopefully not your contract number, login or similar...
Since they probably have hundreds or even thousands of customers, they assign half-numerical names to you for easier administration (for them).

Quote:
Is the IP address the person's PC? If so, what is the "result"?

No. An IP address (V4) is 4 numbers in the range of 0-255 separated by a dot.
I don't have to explain to you what a PC is, do I?
"result"? Of what?

...M
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  #3  
Old September 27th, 2003, 03:11 PM
thegoods thegoods is offline
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Quote:
Originally posted by M.Hirsch

No. An IP address (V4) is 4 numbers in the range of 0-255 separated by a dot.
I don't have to explain to you what a PC is, do I?
"result"? Of what?

...M [/B]


Maybe I didn't make myself clear. I know the PC's address on the Internet is 81.77.255.33, but where does the "user-1825.bbd24tcl.dsl.pol.co.uk" come into play? Why is it needed if the IP (V4) is the address of the PC?

The webpage I referenced uses the term "result" to reference the info returned by the reverse lookup.

If I post to Usenet, my posts show the IP address as my "Posting-Host". If I post to a WWW message board, the board's software records me as user-1825.bbd24tcl.dsl.pol.co.uk. I just don't understand the difference or why there is a need for it. Why is there a need for both if the IP address AND user-1825.bbd24tcl.dsl.pol.co.uk?

Any help is greatly appreciated. Thanks.
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Old September 27th, 2003, 11:56 PM
thegoods thegoods is offline
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Quote:
Originally posted by M.Hirsch

No. An IP address (V4) is 4 numbers in the range of 0-255 separated by a dot.
I don't have to explain to you what a PC is, do I?
"result"? Of what?

...M [/B]


Maybe I didn't make myself clear. I know the PCs address on the Internet is 81.77.255.33, but where does the "user-1825.bbd24tcl.dsl.pol.co.uk" come into play? Why is it needed if the IP (V4) is the address of the PC?

The webpage I referenced uses the term "result" to reference the info returned by the reverse lookup.

If I post to Usenet, my posts show the IP address as my "Posting-Host". If I post to a WWW message board, the board's software records me as user-1825.bbd24tcl.dsl.pol.co.uk. I just don't understand the difference or why there is a need for it. Why is there a need for both if the IP address AND user-1825.bbd24tcl.dsl.pol.co.uk?

Any help is greatly appreciated. Thanks.
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  #5  
Old September 28th, 2003, 12:56 PM
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alexgreg alexgreg is offline
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Quote:
Maybe I didn't make myself clear. I know the PCs address on the Internet is 81.77.255.33, but where does the "user-1825.bbd24tcl.dsl.pol.co.uk" come into play?

It's a DNS PTR record published by your ISP. Here's a list of some more:
Code:
[root@vaio root]# for f in `seq 50`; do name=`dnsname 81.77.255.$f`; echo "81.77.255.$f -> $name"; done
81.77.255.1 -> user-1793.bbd24tcl.dsl.pol.co.uk
81.77.255.2 -> user-1794.bbd24tcl.dsl.pol.co.uk
81.77.255.3 -> user-1795.bbd24tcl.dsl.pol.co.uk
81.77.255.4 -> user-1796.bbd24tcl.dsl.pol.co.uk
81.77.255.5 -> user-1797.bbd24tcl.dsl.pol.co.uk
81.77.255.6 -> user-1798.bbd24tcl.dsl.pol.co.uk
81.77.255.7 -> user-1799.bbd24tcl.dsl.pol.co.uk
81.77.255.8 -> user-1800.bbd24tcl.dsl.pol.co.uk
81.77.255.9 -> user-1801.bbd24tcl.dsl.pol.co.uk
81.77.255.10 -> user-1802.bbd24tcl.dsl.pol.co.uk
81.77.255.11 -> user-1803.bbd24tcl.dsl.pol.co.uk
81.77.255.12 -> user-1804.bbd24tcl.dsl.pol.co.uk
81.77.255.13 -> user-1805.bbd24tcl.dsl.pol.co.uk
81.77.255.14 -> user-1806.bbd24tcl.dsl.pol.co.uk
81.77.255.15 -> user-1807.bbd24tcl.dsl.pol.co.uk
81.77.255.16 -> user-1808.bbd24tcl.dsl.pol.co.uk
81.77.255.17 -> user-1809.bbd24tcl.dsl.pol.co.uk
81.77.255.18 -> user-1810.bbd24tcl.dsl.pol.co.uk
81.77.255.19 -> user-1811.bbd24tcl.dsl.pol.co.uk
81.77.255.20 -> user-1812.bbd24tcl.dsl.pol.co.uk
81.77.255.21 -> user-1813.bbd24tcl.dsl.pol.co.uk
81.77.255.22 -> user-1814.bbd24tcl.dsl.pol.co.uk
81.77.255.23 -> user-1815.bbd24tcl.dsl.pol.co.uk
81.77.255.24 -> user-1816.bbd24tcl.dsl.pol.co.uk
81.77.255.25 -> user-1817.bbd24tcl.dsl.pol.co.uk
81.77.255.26 -> user-1818.bbd24tcl.dsl.pol.co.uk
81.77.255.27 -> user-1819.bbd24tcl.dsl.pol.co.uk
81.77.255.28 -> user-1820.bbd24tcl.dsl.pol.co.uk
81.77.255.29 -> user-1821.bbd24tcl.dsl.pol.co.uk
81.77.255.30 -> user-1822.bbd24tcl.dsl.pol.co.uk
81.77.255.31 -> user-1823.bbd24tcl.dsl.pol.co.uk
81.77.255.32 -> user-1824.bbd24tcl.dsl.pol.co.uk
81.77.255.33 -> user-1825.bbd24tcl.dsl.pol.co.uk
81.77.255.34 -> user-1826.bbd24tcl.dsl.pol.co.uk
81.77.255.35 -> user-1827.bbd24tcl.dsl.pol.co.uk
81.77.255.36 -> user-1828.bbd24tcl.dsl.pol.co.uk
81.77.255.37 -> user-1829.bbd24tcl.dsl.pol.co.uk
81.77.255.38 -> user-1830.bbd24tcl.dsl.pol.co.uk
81.77.255.39 -> user-1831.bbd24tcl.dsl.pol.co.uk
81.77.255.40 -> user-1832.bbd24tcl.dsl.pol.co.uk
81.77.255.41 -> user-1833.bbd24tcl.dsl.pol.co.uk
81.77.255.42 -> user-1834.bbd24tcl.dsl.pol.co.uk
81.77.255.43 -> user-1835.bbd24tcl.dsl.pol.co.uk
81.77.255.44 -> user-1836.bbd24tcl.dsl.pol.co.uk
81.77.255.45 -> user-1837.bbd24tcl.dsl.pol.co.uk
81.77.255.46 -> user-1838.bbd24tcl.dsl.pol.co.uk
81.77.255.47 -> user-1839.bbd24tcl.dsl.pol.co.uk
81.77.255.48 -> user-1840.bbd24tcl.dsl.pol.co.uk
81.77.255.49 -> user-1841.bbd24tcl.dsl.pol.co.uk
81.77.255.50 -> user-1842.bbd24tcl.dsl.pol.co.uk
[root@vaio root]#

The user-xxxx part increments for each IP address in the range.
Quote:
Why is it needed if the IP (V4) is the address of the PC?

From http://cr.yp.to/djbdns/wall.html:

"You could simply leave the relevant data out of DNS. Unfortunately, some silly Internet servers look up the computer name for each incoming IP address, and drop connections from any unlisted computer. A reverse DNS wall lets you connect to these servers: it creates an artificial computer name for every IP address."
Quote:
If I post to Usenet, my posts show the IP address as my "Posting-Host". If I post to a WWW message board, the board's software records me as user-1825.bbd24tcl.dsl.pol.co.uk. I just don't understand the difference or why there is a need for it. Why is there a need for both if the IP address AND user-1825.bbd24tcl.dsl.pol.co.uk?

See above.
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  #6  
Old October 4th, 2003, 04:09 AM
thegoods thegoods is offline
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Thanks for that. That answers my questions.
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