snmptrapd and reverse DNS lookups

I've been troubleshooting a problem for a customer for a while now where it takes about 4-5 hours for a trap received by snmptrapd to be placed into the snmptt spool folder.

Today I think I've identified that DNS lookups are the cause of the delay. I've compared an strace from a test box against the one with problems. This is what sticks out:

connect(10, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("8.8.8.8")}, 16) = 0

Once I saw 8.8.8.8 I knew straight away this is a Google DNS server. Yep I know that's not a great idea.


My question is, how many times does snmptrapd attempt to perform the DNS lookup?

Due to the size of the customers server I'm not going to leave an strace running for 4-5 hours to work this out.

I do understand I can run snmptrapd with the -n argument to stop it attempting to translate source addresses of incoming packets into hostnames OR I just get the customer to stop using and external DNS server.

But that still makes me think, how many times does snmptrapd attempt to perform the DNS lookup?

Is this number of lookups something that can be defined to prevent this going on for 4-5 hours?


Thanks in advance for any answers.

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