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Right OPTION is (B) Wireless networks

The best explanation: The EXTENSIBLE Authentication Protocol (EAP) is an authentication protocol USED to connect a network node to the Internet. It designed through extending the METHODS used by the Point-to-Point Protocol for authentication.

Right answer is (a) Denial-of-SERVICE attack

To explain I WOULD say: In a Denial of Service attack, the attacker won’t let the victims access the network by using a certain method that ensures that an essential network resource is unavailable to the victim. The methods that the attacker can USE are VULNERABILITY attack, bandwidth flooding and CONNECTION flooding.

The correct choice is (d) All of the mentioned

For explanation I would SAY: AH ensures that there is no retransmission of DATA from an unauthorized source, and protects against data TAMPERING. ESP provides with content protection and ensures that there is integrity and confidentiality for the message. IKE is used to make sure that only the intended sender and receiver can ACCESS the message.

Right CHOICE is (a) Entire IP packet

Explanation: In the tunnel mode, IPSec adds control bits into the packets to ENCRYPT the entire packet between the IPSec endpoints. Using encryption, it PROVIDES secure communication between the two endpoints.

Right option is (b) Network layer

Easy explanation: IPSec is a set of protocols used to PROVIDE authentication, data integrity and confidentiality between two machines in an IP network. In the TCP/IP MODEL, it provides SECURITY at the IP layer i.e. the network layer.

The correct answer is (c) Both MAC address and IP address

The BEST EXPLANATION: The DHCP snooping is done to PREVENT unauthorized IP addresses being offered by unauthorized SERVERS. This features allows only SPECIFIC mac addresses and IP addresses to access the network.

The CORRECT option is (a) techniques applied to ensure the SECURITY of an existing DHCP infrastructure

For explanation I WOULD say: DHCP snooping is a security feature that is used in OS of a NETWORK in the layer 2. This technology prevents unauthorized DHCP servers offering IP addresses to DHCP clients.

The correct answer is (c) address RESOLUTION protocol

Easiest explanation: ARP abbreviation for address resolution protocol is used for mapping IP addresses to MAC addresses that are present in the local network.

The CORRECT choice is (a) UDP broadcast

To explain I would say: DHCP actually EMPLOYS a CONNECTIONLESS service, which is PROVIDED by UDP, since TCP is connection oriented. It is implemented with two UDP port numbers 67 and 68 for its operations.

The CORRECT choice is (b) 67

For EXPLANATION I would say: 67 is the UDP port NUMBER that is USED as the destination port of a server. Whereas UDP port number 68 is used by the client.

The CORRECT option is (a) for a LIMITED PERIOD

To elaborate: The IP address offered to a client is only for a limited period of time. There is actually a certain amount of time that the client can use and KEEP this IP address.

Right choice is (d) all of the mentioned

For explanation: SSH USED public key AUTHENTICATION, PASSWORD authentication, Host BASED authentication, keyboard authentication and authentication of servers.

The correct CHOICE is (a) RCP protocol

To explain: RCP is the abbreviation for Rate Control Protocol is a congestion control ALGORITHM for FAST USER RESPONSE times.

The correct CHOICE is (c) physical layer

The best I can EXPLAIN: SSH2 is a more secure, portable and EFFICIENT version of SSH that INCLUDES SFTP, which is functionally similar to FTP, but is SSH2 ENCRYPTED.

Correct CHOICE is (d) All of the mentioned

The best EXPLANATION: SCP (Secure copy protocol), SFTP (SSH FILE Transfer Protocol) and Rsync all are file transfer protocols which are USED by SSH.

The CORRECT answer is (c) both TELNET and rlogin

Easy EXPLANATION: SSH is more SECURED then telnet and rlogin.

Correct answer is (B) port 22

The BEST I can explain: Port 22 is USED for contacting ssh SERVERS, used for file transfers (SCP, sftp) and also port forwarding.

The correct answer is (a) public-key cryptography

For explanation I WOULD say: Public ENCRYPTION key is SLOWER but more flexible. Every cryptographic security SYSTEM requires a private key for private access and a public key for location.

The CORRECT choice is (c) both unix-like and WINDOWS systems

To explain: SSH isn’t confined to a certain NETWORK or operating system. It can be implemented over DIFFERENT networks and on different operating systems.

The correct CHOICE is (d) all of the mentioned

Easy explanation: SSH PROVIDES high encryption and security FEATURES while COMMUNICATING through a network. It is a cryptographic network protocol.

The correct option is (c) a SINGLE hostname may CORRESPOND to a single IP ADDRESS

To elaborate: It NEED not be that a single hostname will correspond to a ip address. For example facebook.com and fb.com both correspond to same ip address. So there can be multiple hostnames for a single ip address.

Right ANSWER is (a) distributed database SYSTEM

Explanation: A DOMAIN name system is MAINTAINED by a distributed database system. It is a collection of multiple, logically interrelated databases distributed over a computer network.

Correct answer is (d) internet corporation for assigned names and numbers

Easy EXPLANATION: The ICANN (Internet Corporation for Assigned Names and Numbers) DEALS with IP address space allocation, protocol identifier assignment, generic and country code Top Level DOMAIN NAME system management (gTLD and ccTLD).

Correct OPTION is (b) *

Easiest explanation: A wildcard DNS record MATCHES REQUESTS to a non EXISTENT domain name. This wildcard DNS record is specified by using asterisk “*” as the starting of a domain name.

Right choice is (a) dynamic DNS

For EXPLANATION: Dynamic DNS or in short DDNS or DynDNS helps in automatically updating a NAME SERVER in the DNS. This does not require manual EDITING.

Correct OPTION is (a) server asks to the ROOT server

Easy explanation: Root name servers are ACTUALLY very important and critical as they are the FIRST STEP in translating human readable hostnames into IP addresses for carrying out communication.

The correct ANSWER is (b) by contacting remote DNS server

The best I can explain: Whenever a REQUEST is RECEIVED at server from other DOMAINS, it HANDLES this situation by contacting remote DNS server.

The CORRECT option is (b) DNS resolver

Easiest explanation: DNS client also KNOWN as DNS resolver also known as DNS LOOKUP helps to RESOLVE DNS requests using an external DNS server.

Right CHOICE is (c) user’s word PROCESSOR

Easy EXPLANATION: SMTP can only be used to send messages to user’s terminal, email CLIENT or mailbox. A stand-alone word processor cannot be connected to a network, so it won’t be possible to DELIVER messages to it.

Correct answer is (a) open mail relay

For EXPLANATION I WOULD say: Anyone can send an e-mail through an Open Mail Relay server so it acted like a free relay for email agents to forward their mails through. Open Mail RELAYS are now unpopular because they can be USED by attackers to perform man-in-the-middle attacks.

Correct OPTION is (a) message transport

Explanation: As the NAME suggests, Simple Mail Transfer Protocol is only responsible for “how” the message is TRANSFERRED i.e. Transport of the message. Other protocols such as TCP are used to provide other SERVICES like encryption for the messages.

Correct choice is (a) IP address

For EXPLANATION I would say: The client needs to know the IP of its INITIAL SMTP SERVER as it has to send the mail first to that server and then the server forwards the mail ahead on behalf of the USER.

The correct CHOICE is (b) an SMTP extension

Explanation: ODMR is an extension to SMTP, in which mails are RELAYED to the receivers after they are authenticated. It ALLOWS only the authorized receivers to receive the mail.

Correct option is (d) 25

Easiest explanation: Port 21 is used for FTP control connection, port 22 is used by SSH, and port 23 is used by TELNET.

Correct option is (a) SMTPS

The best explanation: SSMTP is a simple mail transfer PROGRAM to send mail from a local PC to a mail host. SNMP is a NETWORK management protocol. STARTTLS connections are secured by TLS.

The correct choice is (a) TCP

Explanation: Since TCP is a reliable PROTOCOL, it’s more EFFICIENT to use TCP protocol for e-mail transfer. TCP also provides more security than other TRANSPORT layer protocols.

The correct option is (d) TWO UAs and two MTAs

For explanation I would say: The sender’s User Agent (UA) submits the message to a Message Transfer Agent (MTA). Then the MTA sends the message to another MTA i.e. a mail RELAY. Then the RECEIVER receives the message from the mail relay WHENEVER it is AVAILABLE.

Correct option is (a) Microsoft Outlook

For explanation: AMONG the options, only Microsoft Outlook is an e-mail agent. Google is a search engine and Facebook, and TUMBLR are social networking platforms. Gmail and ALPINE are some other examples of e-mail agent.

Correct option is (a) Zero or more SMTP TRANSACTIONS

To explain I would say: An SMTP session CONSISTS of SMTP transactions only even if no transactions have been PERFORMED. But no transactions in the session MIGHT mean that the session is inactive or is just initiated.