This read-write INTEGER (noAuthentication(1)/simplePassword(2)/md5(3)), defaulting to noAuthentication, specifies, per its source description, what type of authentication is applied to received RIP packets on this interface: none, a clear-text password stored in zhRip2IfConfAuthKey, or an MD5 digest per RFC 1321 also stored in that same object. Admins set this to md5 rather than simplePassword whenever possible, since MD5 avoids transmitting the shared secret in clear text on the wire. For example, setting this to md5(3) between two routers exchanging RIP updates over a shared segment would prevent a third party from easily forging or replaying RIP updates using a sniffed clear-text password.