Which of the following password authentication schemes enables a user with a domain account to
log on to a network once, using a
password or smart card, and to gain access to multiple computers in the domain without being
prompted to log in again?

A.
Single Sign-On

B.
One-time password

C.
Dynamic

D.
Kerberos

Explanation:
Single Sign-On (SSO) is a system capability that enables users to access a number of
applications without having to log on and/or provide a
password to each application. In SSO, a user can access all computer applications and systems where
he has access permission without
entering multiple passwords. This reduces human error and systems failure and is therefore highly
desirable. There are many commercial SSO
solutions available in the market. Some of them are as follows:
Central Authentication Service (CAS)
The Dutch NREN

CoSign
Enterprise Single Sign-On (E-SSO)
Web Single Sign-On (Web SSO)
Security Assertion Markup Language (SAML)
Direct SSO
Shibboleth
Answer option B is incorrect. A one-time password (OTP) is a password only valid for a single login
session or transaction. OTP avoids a
number of shortcomings that are associated with traditional passwords. The most important
shortcoming that is addressed by OTP is that OTP
is not vulnerable to replay attacks. If a potential intruder manages to record an OTP that was already
used to log into a service or to conduct
a transaction, he will not be able to abuse it since it will be no longer valid.
Answer option D is incorrect. Kerberos is a secure protocol that supports ticketing authentication. A
ticket is granted in response to a client
computer authentication request by the Kerberos authentication server, if the request contains valid
user credentials and a valid Service
Principal Name (SPN). The ticket is then used by the client computer to access network resources. To
enable Kerberos authentication, the
client and server computers must have a trusted connection to the domain Key Distribution Center
(KDC). The task of KDC is to distribute
shared secret keys to enable encryption.
Answer option C is incorrect. In the dynamic password authentication scheme, passwords are
changed after a specified time or time interval.