cd /usr/local/share/snmp/mibs
View MIBS with
ls
Example: View content of HOST-RESOURCES-MIB.txt and search for "OBJECT-TYPE"
You wil find: hrSystemUptime OBJECT-TYPE
Extract OID with:
snmptranslate -m +HOST-RESOURCES-MIB -IR -On hrSystemUptime
Result is: .1.3.6.1.2.1.25.1.1
OID you should use is: .1.3.6.1.2.1.25.1.1.0
Use: SNMP Tester to check OID