Finding RR's of s certain type

phn at icke-reklam.ipsec.nu phn at icke-reklam.ipsec.nu
Thu Dec 19 19:40:09 UTC 2002


Bryan Zimmer <baz at baz-tech.com> wrote:
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> Hello,

> I have been running a name server for a year or so. I am curious about a
> few more unusual RR types such as SRV and LOC. This is primarily in
> intellectual curiosity. rather than a specific need to find the records.

> How would one go about trying to find these relatively rare records? It
> could take forever and generate uncountably many queries just to pick
> domains at random or even from a list (such as culled from the cache or
> named.run), asking for LOC or SRV records, for example.

> Is there any way this is commonly done? My understanding is that the
> query is directed to a name server regarding a host or domain, never in
> general, "please direct me to a SRV record".

> I am also inexperienced enough that I would love to see DNS database
> files for large zones with many hosts. My servers are authoritative for
> 14 hosts or so. I understand most name server operators don't allow
> transfers to merely anyone for security reasons, but if anyone happens t=
o
> be responsible for a large DNS database (i.e. "db" file in UNIX/BIND),
> please let me know. The data would only be for study and never
> distributed or used in any way.

> Thank you,

> Bryan Zimmer
> baz at sendnetworking.com

SRV records ( RFC 2782) describes a general way to express what ip and
portnumber to find a certain service. It also contains ways of
expressing "prioryties" and would be very useful for URL's=20
( the down side is that no current browser does this). MS uses
SRV records as a way to find servers for functions.


LOC records (RFC 1876) is a formalized way of expressing a position=20
"1. Abstract

   This memo defines a new DNS RR type for experimental purposes.  This
   RFC describes a mechanism to allow the DNS to carry location
   information about hosts, networks, and subnets."

Exanples of real ones may be found at :

ipsec.se which describes by companys location.

> dig ipsec.se loc

; <<>> DiG 8.3 <<>> ipsec.se loc
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUERY SECTION:
;;      ipsec.se, type =3D LOC, class =3D IN

;; ANSWER SECTION:
ipsec.se.               1D IN LOC       57 42 27.000 N 11 56 41.200 E 5.00=
m 10.00m 5.00m 6.00m


SRC records ( again an example from my own zone :
> dig _http._tcp.zonecheck.ipsec.se srv

; <<>> DiG 8.3 <<>> _http._tcp.zonecheck.ipsec.se srv
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3
;; QUERY SECTION:
;;      _http._tcp.zonecheck.ipsec.se, type =3D SRV, class =3D IN

;; ANSWER SECTION:
_http._tcp.zonecheck.ipsec.se.  1D IN SRV  10 0 80 zonecheck.manet.nu.

expresses that the service named "zonecheck.ipsec.se" for service "http"
over "tcp" runs on port 80/tcp on zonecheck.manet.nu.







--=20
Peter H=E5kanson=20=20=20=20=20=20=20=20=20
        IPSec  Sverige      ( At Gothenburg Riverside )
           Sorry about my e-mail address, but i'm trying to keep spam out,
	   remove "icke-reklam" if you feel for mailing me. Thanx.


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