The value of tmnxOamPingHistoryDnsAddress indicates the
Internet address that was resolved from the name specified
in tmnxOamPingCtlDnsName by a 'dnsPing' test.
If this was not a 'dnsPing' test or the dns name specified
in tmnxOamPingCtlDnsName could not be resolved, the value of
this object will be reported as ''H (empty string).