Reverse Namelookup for a classless subnet

Sumit Mehrotra sumit at cs.bu.edu
Wed Nov 15 01:50:43 UTC 2000


Hi Users


Here is the INFORMATION first about my setup ( QUESTIONS follow)

I have 2 IP addresses at present, with name servers provided by my ISP. Now, I am trying to make a NS ( running in a different domain altogether, from the 2 IP addresses), the Primary NS for a webservers running on these 2 IPs.

I have set up the configuration files and dealt with the firewall issues. 

At present I can do a nslookup/dig for the name of the webservers from inside and outside the domain that the NS resides in ( behind firewalls). 

For the reverse lookup, from inside the NS domain I get the following answer :
DIG
---
; <<>> DiG 8.2 <<>> @dhruv.bu.edu 20.10.197.128.in-addr.arpa ptr 
; (1 server found)
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;;	20.10.197.128.in-addr.arpa, type = PTR, class = IN

;; ANSWER SECTION:
20.10.197.128.in-addr.arpa.  1D IN PTR  pharos.bu.edu.

;; Total query time: 0 msec
;; FROM: dhruv.bu.edu to SERVER: dhruv.bu.edu  128.197.14.80
;; WHEN: Tue Nov 14 20:41:14 2000
;; MSG SIZE  sent: 44  rcvd: 71


Notice that the Authority Bit is not set, when it should have been set.

For Outside the NS domain, I get the same answer.

Additionally, the reverse nslookup for the address fails unless I add an in-addr.arpa to it. (This baffles me!)

QUESTIONS :

Is it something to do with delegation of the in-addr.arpa space by the ISP to my new NS?

If so will it be done automatically, if I go and change the NS for it, on the Web based form that they have?

Thanks
- Sumit




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