[luau] Re: no answers from roadrunner dns

William N Luoma luoma at hawaii.edu
Tue Mar 4 16:21:01 PST 2003


+The TTL for news.google.com is set to 5 minutes. However, google
+sets the TTL for their nameservers to be 4 days, but RR's
+configuration limits the max TTL to 24 hours. From my vantage
+point, the DNS server does cache the results. What are you seeing
+that I am not?

> Here's a trace from dns1.hawaii.rr.com:
> DnsClient::ReadResponse recv'd: 179 bytes 
> from: UDPClientConnection: 24.25.227.64:53 
> dn: news.google.com

+I have never seen a utility that queries DNS in such a way.
+I use dig to troubleshoot DNS myself.
+
+-Vince

Hi Vince. I should try dig. i wrote my own resolver that just
writes/reads to port 53. And whenever I query news.google.com
road runner sends back a packet with zero answer records. Other name 
servers I've run this client on seem to cache a lot more. 
RR just gives a lot of zero answer record responses. What this means
is that I have to parse the additional records (ar), and then
open up another socket to the ip mentioned in the ar (a more
authoritative nameserver), and hope it sends back some answer records. 
all this takes time and bandwidth. especially when most of the 
secondary lookups have to go to the mainland and back. I assume this 
has to happen when anyone opens a browser to some dns that isn't cached 
(calling gethostbyname rather than doing it manually).

It also seems like the rr nameservers aren't doing any recursion
even tho i set the RD bit on my query and the reply has the RA 
(recursion availble) buit set. 

And Warren. I began using the 32,34,36 addresses you mentioned,
but thought I was using the wrong names servers since 
I was getting so many responses with zero answer records,
so i switched to dns1.hawaii.rr.com and dns2.hawaii.rr.com.
But these two behave the same as three above. 
I suppose it is just their policy.

thanks,
Bill





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