2013 Latest Cisco 350-001 Exam Section 3: Applications (6 Questions)
QUESTION NO: 1
With regard to the File Transfer Protocol (FTP), which of the following statements are true?
A. FTP always uses one TCP session for both control and data.
B. With passive mode FTP, both the control and data TCP sessions are initiated from the client.
C. With active mode FTP, the server used the “PORT” command to tell the client on which port it wished to send the data.
D. FTP always uses TCP port 20 for the data session and TCP port 21 for the control session.
E. FTP always uses TCP port 20 for the control session and TCP port 21 for the data session.
For a detailed discussion on FTP refer the link below.
A. FTP always uses two separate TCP sessions, one for control and one for data.
C. In FTP active mode the client (not the server) uses the PORT command to tell the
server on which port it expects the server to send the data.
D, E. These statements are too general as FTP behaves differently based on whether the
mode of operation is active or passive.
QUESTION NO 2:
You use a telnet application to access your Internet router. What statement is true
about the telnet application?
A. Telnet does not use a reliable transport protocol.
B. Telnet is a secure protocol because it encrypts every message sent.
C. Telnet sends user names, passwords and every other message in clear text.
D. Telnet encrypts user names, passwords but sends every other message in clear text.
E. Telnet uses UDP as transport protocol.
Telnet is inherently insecure since it sends all data in plain text. This is an important consideration when using telnet across the Internet. For this reason, more secure remote access applications such as SSH have been developed.
A, E: Telnet uses TCP port 23, which is a reliable protocol.
B, D: No portion of a telnet packet is encrypted or authenticated.
QUESTION NO 3:
What is the method used by SMTP servers on Internet to validate the e-mail address
of the message sender?
A. It checks the user address with the MTA sending the message.
B. It validates the domain of the sender address with a DNS server.
C. It does not check the sender address.
D. It checks if the IP address of the MTA sending the message is not spoofed.
E. It checks if the domain of the MTA sending the message matches with the domain of the sender of the message.
When e-mail is handed off today from one organization to another, as a rule no authentication of the sender of the e-mail or the computers delivering it on the sender’s behalf takes place. Due to the spread of SPAM and emails coming from spoofed locations, measures can be taken to minimize their effect. The MTA Authentication Records in DNS Internet Draft describes mechanisms by which a domain owner can publish its set of outgoing Mail Transfer Agents (MTAs), and mechanisms by which SMTP servers can determine what email address is allegedly responsible for most proximately introducing a message into the Internet mail system, and whether that introduction is authorized by the owner of the domain contained in that email address. However, as a standard rule today, no SMTP server is required to take any security measures to validate the message sender.
QUESTION NO: 4
Upon which protocol or protocols does TFTP rely on?
A. IP and TCP
E. ICMP and UDP
The Trivial File Transfer Protocol (TFTP) is a simplified version of FTP that allows files to be transferred from one computer to another over a network, usually without the use of client authentication (for example, username and password). TFTP uses UDP port 69.
QUESTION NO: 5
Identify the TCP port numbers with their associated programs: 443, 389, 137, 110,
and 23 in the proper sequence:
A. BGP, POP3, SNMP, TFTP, Telnet
B. LDAP, SNMP, TFTP, POP3, Telnet
C. HTTPS, SNMP, POP3, DNS, Telnet
D. Finger, DHCP Server, NetBios Name Server, POP3, Telnet
E. HTTPS, LDAP, NetBios Name Server, POP3, Telnet
F. None of the above
The following shows the TCP port numbers used with the associated applications: HTTPS (secure WWW): 443 LDAP: 389 on the directory server NetBios Name Server: 137 POP3: 110 Telnet: 23
A. BGP uses TCP port 179.
B, C. SNMP uses TCP port 161.
D. Finger uses TCP port 79 while DHCP uses 67 (BOOTP)
A complete list of TCP port numbers and their assignments can be found here:
QUESTION NO: 6
On what lower level transport protocol does SNMP rely and why?
A. TCP, because SNMP requires the reliability of TCP, which ensures packets are transmitted reliably, in event that a packet is lost in the network.
B. UDP, because SNMP is an application that does not require the reliability provided by TCP.
C. IP, because SNMP requires the reliability of IP packets, which can detect lost packets and retransmit them if required.
D. UDP, because SNMP is an application that requires the reliability of UDP and UDP’s ability to detect lost packets and retransmit them.
E. TCP, because SNMP is an application that does not require detection and retransmission of lost packets.
SNMP uses the User Datagram Protocol (
UDP) as the transport protocol for passing data between managers and agents. UDP, defined in RFC 768, was chosen over the Transmission Control Protocol (TCP) because
NMS when datagrams (packets) are sent back and forth. This aspect of UDP makes it unreliable, since there is no acknowledgment of lost datagrams at the protocol level. It’s up to the SNMP application to determine if datagrams are lost and retransmit them if it so desires. This is typically accomplished with a simple timeout. The NMS sends a UDP request to an agent and waits for a response. The length of time the NMS waits depends on how it’s configured. If the timeout is reached and the NMS has not heard back from the agent, it assumes the packet was lost and retransmits the request. The number of times the NMS retransmits packets is also configurable. At least as far as regular information requests are concerned, the unreliable nature of UDP isn’t a real problem. At worst, the management station issues a request and never receives a response. For traps, the situation is somewhat different. If an agent sends a trap and the trap never arrives, the NMS has no way of knowing that it was ever sent. The agent doesn’t even know that it needs to resend the trap, because the NMS is not required to send a response back to the agent acknowledging receipt of the trap. The upside to the unreliable nature of UDP is that it requires low overhead, so the impact on your network’s performance is reduced. SNMP has been implemented over TCP, but this is more for special-case situations in which someone is developing an agent for a proprietary piece of equipment. In a heavily congested and managed network, SNMP over TCP is a bad idea. It’s also worth realizing that TCP isn’t magic, and that SNMP is designed for working with networks that are in trouble — if your network never failed, you wouldn’t need to monitor it. When a network is failing, a protocol that tries to get the data through but gives up if it can’t is almost certainly a better design choice than a protocol that will flood the network with retransmissions in its attempt to achieve reliability.
SNMP uses the UDP port161 for sending and receiving requests, and port
162 for receiving traps from managed devices. Every device that implements SNMP
must use these port numbers as the defaults, but some vendors allow you to change the default ports in the agent’s configuration. If these defaults are changed, the NMS must be made aware of the changes so it can query the device on the correct ports.
SNMP use of UDP port numbers.
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