I am having some problems with sendmail when it is looking up DNS for mail delivery or to resolve an MX record on inbound email. When we captured the network traffic, it was determined that sendmail is doing a request for all records whenever it is resolving a domain name. I would have expected that it would only be looking up an MX record. Is that normal? Can this be changed?
I do not have a nsswitch.conf on this server. DNS is not located on the same server as sendmail. Do I need to have this configuration if DNS is not on this server?
What are you expecting to see when I do an nslookup? If I don't set any type, I appear to get a number of A records for the domain that I queried.
Your problem description stated that you are using DNS. If you are using DNS, then you need an nsswitch.conf file in order to figure out how to resolve each DNS name. Also, you need a resolv.conf file that lists your DNS servers.
I have configured DNS using the set_parms addl_netwrk command. Does this not set up this server to use the specified DNS? Does Sendmail not use this configuration?
When I looked in the directory that you stated, there is no nssswitch.conf file. If the nsswitch.conf file is missing, doesn't it use a default configuration? Would this not be adequate or does it need hard coded information?
You should have the following entry in your /etc/nsswitch.conf file:
hosts: dns [NOTFOUND=continue UNAVAIL=continue] files
Make sure that /etc/resolv.conf contains your nameserver details otherwise sendmail will assume that you are trying to resolve names using the local machine.
I created the nsswitch.conf from the nsswitch.hp_defaults file and I verified the entries in resolv.conf. Now whenever I try to clear the queue (Sendmail -q -v)I get an "NIS map mail.aliases specified but NIS not running" message. It still seems to run the command but I get this message. How do I get rid of this message and do I need any of the entries in nsswitch.conf other than the hosts: DNS entry.
