Subject: Statistics on IN-ADDR.ARPA hosts

From: Shane Kerr <[email-masked]>
Date: Fri, 18 Aug 2000 12:52:27 +0200

Okay, I got the list of hosts that connected to the RIPE Whois server 
on 2000-08-16, and did some checking.  

18367 unique hosts, 4441 of which had no host name

So about 24% didn't have a valid host name.  I ran the hosts without 
names through a program that called gethostbyname() and returned the 
h_errno and timed the lookup.  The results:

 176, 0.911s -> Successful lookups (meaning 4% of the original lookups 
                work now).

3908, 0.637s -> Authoritative Answer Host not found (88% seem to have 
                a working IN-ADDR server, albeit one giving incorrect 
                answers, since the hosts clearly exist).

 350, 12.25s -> Server failure (8% do NOT have a working IN-ADDR 
                server).

   7, 1.030s -> Valid name, no PTR record (???)

It looks like only 2% of the hosts in this sample have what I would 
consider a true problem - the ones with a server failure who took an 
average of 12 seconds to complete a DNS lookup.

In some sense this may be unimportant.  OTOH, if this is representative 
of the larger Internet, and if 10% of the 1.1 billion announced IP's on 
the Internet actually have an active host, then this over 2 million 
computers.  2000000 hosts * 10 seconds * 1 DNS lookup is more than 230 
days of poor schmucks waiting idly at their keyboards, wondering why 
the Internet is so damn slow.  :)

Shane

---

From: Shane Kerr <[email-masked]>
Date: Fri, 18 Aug 2000 13:42:41 +0200

> Why so long. It shouldn't take 12 seconds for a server to figure out that
> it doesn't have a table available for a zone. More likely the server
> thinks that somebody else has the data and it's trying to contact that
> other somebody? This could be a result of aliased PTRs, connectivity
> problems, and other issues. In all cases the delegation is messed.

My guess is that its a zone delegated incorrectly.  I.e. the network 
administrator hasn't bothered to let his DNS upstream know about his 
server.

> Is this average time? Got a distribution?

This is the average time.  A distribution, queries on the Y axis, 
seconds on the X axis, of this data set:

121.0 #                                                            
116.0 #                                                            
110.9 #                                                            
105.9 #                                                            
100.8 #                                                            
 95.8 #                                                            
 90.7 #                                                            
 85.7 #                                                            
 80.7 #                                                            
 75.6 #                                                            
 70.6 #                                                            
 65.5 #                                                            
 60.5 #                                                            
 55.5 ##                                                           
 50.4 ##                                                           
 45.4 ##                                                           
 40.3 ##                                                           
 35.3 ##                                                          #
 30.2 ###                                                         #
 25.2 ###                                                         #
 20.2 ### #                                                       #
 15.1 #####   #                                                   #
 10.1 ######  #                                                   #
  5.0 ####### #                                                   #
      -------------------------------------------------------------
      0                            40                            80 

Nothing too surprising here.                     
 
> Were queries sent with RD?

I'm afraid I don't know what RD is.  Too damn much jargon on the 
Internet.

Shane