If I issue a 'wget' command to a symbolic IP address that is know to be bad, I am getting a HTTP return code of 200:

# wget obviousbogus.com
--2011-10-06 10:02:07-- http://obviousbogus.com/
Resolving obviousbogus.com... 92.242.140.30
Connecting to obviousbogus.com|92.242.140.30|:80... connected.
HTTP request sent, awaiting response... 200 OK

If I enter a numeric IP, this does not happen--wget fails and times out.

The same thing is happening inside one of my applications. To check the validity of a URL, I do an open of TCP port 80 and find that bad URLs are marked as valid. (The app is in MUMPS, which is probably not familiar to most people on this list.)

I would blame the DNS nameserver, but on Windows, using the same nameserver, the application works correctly.

I can probably figure out how to work around this, but if anybody has any understanding of why this might be happening on Linux and not Windows, I would appreciate the insight.

My OS is RHEL 5.6.

Thanks,
Sanford Stein
CyberTools Inc.

I bet obviousbogus.com is in your /etc/hosts file

please give us the output of to narrow down on the problem:

16pide,

Output that you requested follows:
-----------------------------------------------------------------------------------------------
[root@maple mbp5vdrzqtui]# grep hosts /etc/nsswitch.conf
#hosts: db files nisplus nis dns
hosts: files dns
[root@maple mbp5vdrzqtui]# cat /etc/resolv.conf
search cybertoolsforlibraries.com
nameserver ns1.net1plus.com
nameserver ns2.net1plus.com
nameserver ns3.net1plus.com
nameserver 198.6.1.5
#nameserver 207.77.56.2
#nameserver 140.186.94.18
#nameserver 207.77.56.10
#nameserver 66.205.85.4
#nameserver 66.205.86.4
[root@maple mbp5vdrzqtui]# nslookup obviousbogus.com
Server: 198.6.1.5
Address: 198.6.1.5#53

Non-authoritative answer:
Name: obviousbogus.com
Address: 92.242.140.30

[root@maple mbp5vdrzqtui]# grep obviousbogus /etc/hosts
[root@maple mbp5vdrzqtui]# nslookup anotherobviousbogus.com
Server: 198.6.1.5
Address: 198.6.1.5#53

Non-authoritative answer:
Name: anotherobviousbogus.com
Address: 92.242.140.30

[root@maple mbp5vdrzqtui]#
--------------------------------------------------------------------------------------

No,obviousbogus is not in /etc/hosts, but the nslookup output is interesting. The DNS server is resolving any bad address as 92.242.140.30.
If I change the primary DNS server to 75.75.75.75 in /etc/resolv.conf, everything works properly.

So it would seem that this is a DNS and not a Linux issue, EXCEPT that if I use ns1.net1plus.com as my DNS server on Windows, it handles
bad addresses properly.

Thanks,
SS

I figured this out. The 4th nameserver in my resolv.conf (198.6.1.5 or uunet.com) was choosing to resolve all bad addresses as 92.242.140.30.
When Linux could not resolve the name via the first three nameservers, it deferred to the fourth one. So if I just eliminate 198.6.1.5 from resolv.conf everything works.

And ns1.net1plus.com worked on Windows because Windows only allows you one nameserver (and then probably defaults to something they choose).
When I tried uunet on Windows, it also failed.

Makes sense. 16pide,thanks for responding.