[WBEL-users] Re: [wbel-u] How can I speed up sendmail

[R P Herrold]

On Sun, 27 Feb 2005, Lewis Culbertson wrote:

> How do I do that?

>> This is usually a sign of a messed up resolver.  Verify that
>> the nameserver which are pointed to in /etc/resolv.conf are
>> alive and answering.

Examine /etc/resolv.conf   It should look like this:

[herrold at dhcp11 herrold]$ cat /etc/resolv.conf
nameserver 66.195.224.112
nameserver 65.43.29.92
[herrold at dhcp11 herrold]$

It may have additional lines such as the domain and search 
lines -- see man 5 resolv.conf for a braoder explaination. 
there should NOT be and dead nameservers in that listing, for 
that will cause timeout problems.  If possible, you should 
also run a local DNS setup if you use an interior RFC 1918 
network, such as behind a NAT, because resolving interiorn 
hosts names also ahs to work for sendmail to work speedily (it 
does reverse DNS lookups, as part of anti-spam measures) and 
if the information for the lookup is missing, another timeout 
gets built into the mix.


Those two nameservers are up -- you can test such matters 
thus:

    dig www.cnn.com @66.195.224.112

(dig is in the bind-utils package)

which should return a line looking like this:

[herrold at dhcp11 herrold]$ dig www.cnn.com @66.195.224.112

; <<>> DiG 9.2.4 <<>> www.cnn.com @66.195.224.112
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63354
;; flags: qr rd ra; QUERY: 1, ANSWER: 9, AUTHORITY: 4, 
ADDITIONAL: 0

;; QUESTION SECTION:
;www.cnn.com.                   IN      A

;; ANSWER SECTION:
www.cnn.com.            300     IN      CNAME   cnn.com.
cnn.com.                300     IN      A       64.236.24.4
cnn.com.                300     IN      A       64.236.24.12
cnn.com.                300     IN      A       64.236.24.20
cnn.com.                300     IN      A       64.236.24.28
cnn.com.                300     IN      A       64.236.16.20
cnn.com.                300     IN      A       64.236.16.52
cnn.com.                300     IN      A       64.236.16.84
cnn.com.                300     IN      A       64.236.16.116

;; AUTHORITY SECTION:
cnn.com.                600     IN      NS      twdns-03.ns.aol.com.
cnn.com.                600     IN      NS      twdns-04.ns.aol.com.
cnn.com.                600     IN      NS      twdns-01.ns.aol.com.
cnn.com.                600     IN      NS      twdns-02.ns.aol.com.

;; Query time: 337 msec
;; SERVER: 66.195.224.112#53(66.195.224.112)
;; WHEN: Sun Feb 27 09:53:18 2005
;; MSG SIZE  rcvd: 270

It took 337 mSec to get the reply from server 66.195.224.112; 
that server in turn probably queried the top level DNS root 
servers, and were in turn referred to any of the 
twdns-*.ns.aol.com. servers for its answer.

-- Russ Herrold