OID value: 1.3.6.1.2.1.4.2
OID description:
ipDefaultTTL OBJECT-TYPE SYNTAX INTEGER ACCESS read-write STATUS mandatory DESCRIPTION "The default value inserted into the Time-To-Live field of the IP header of datagrams originated at this entity, whenever a TTL value is not supplied by the transport layer protocol." ::= { ip 2 }
See also the OID Repository website reference for 1.3.6.1.2.1.4.2