>Is there a way to test to see if a specific RBL is active and
>responding?

tail your maillog file.  if you see something like "RBL nslookup failure 
for ... " then that RBL is down

>I have since reviewed our other listed RBLs and found the following ones
>in our configuration which do not resolve on DNS lookups:
>
>spews.relays.osirusoft.com
>socks.relays.osirusoft.com
>dialups.relays.osirusoft.com
>pamsites.relays.osirusoft.com
>spamhaus.relays.osirusoft.com
>sbl.spamhaus.org
>proxies.relays.monkeys.com
>bl.spamcop.net
>list.dsbl.org
>
>Since these hosts do not resolve with DNS lookups, does this mean they
>are offline and no longer functional?

something else is wrong. osirusoft was and my be under a DoS attack.

I've seen spamcop working recently, but the situation can change quickly.

>Here is another odd nslookup.  When I do a nslookup on
>relays.osirusoft.com using our name servers (a FreeBSD one and a Win32
>one), I get only 1 IP listed (168.103.238.114).  However, if I perform
>the same lookup using any other name server, I get 6 IPs listed
>(168.103.21.153, 168.103.21.154, 168.103.21.155, 168.103.238.113,
>168.103.238.114, 168.103.238.115).  I checked the SOA record and the
>serial number on our name servers match the serial number on the other
>name servers I used.  Why is this happening?

different results from different NS can be due to differing TTLs on the 
individual records and how old they are in each DNS.  If there are 5 
records in an answer, but with different TTLs, the DNS will answer with 
whatever records haven't expired, and will not go get a new answer since it 
has some records cached.

Len


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