if device does not have a particular oid that is queried, zabbix logs and reports on the frontend :
error: OID [.1.3.6.1.4.1.11.2.14.11.1.2.6.1.4.2] value has unknow type [0x81]

0x81 is reported by net-snmp on the same box as : No Such Instance currently exists at this OID

to ease the debugging and provide more useful messages, it would be nice to display such a message instead of the quite mysterious 0x81 type one.