CCNA试题1-19答案
1. [OxNx] During a TFTP transfer using Cisco Routers what is the numeric value, in decimal, of the destination port field of the User Datagram Protocol (UDP) header?
a) 96
b) 47
c) a random number above 1024
d) 69
e) none of the above
Answer
d) 69
Here is a sampling of other port numbers and the application they are associated with. The first 8 of these protocols are automatically forwarded through the router by using the helper-address command
Trivial File Transfer (TFTP) (port 69)
Domain Name System (port 53)
IEN-116 Name Server (port 42)
Time service (port 37)
NetBIOS Name Server (port 137)
NetBIOS Datagram Server (port 138)
Boot Protocol (BootP) client and server datagrams (port 67)
TACACS service (port 49)
Simple Mail Transfer Protocol (25)
File Transfer Protocol (21)
Simple Network Management Protocol (161)
2. [CxNx] What is the standard encapsulation method used by Cisco routers for the Internet Protocol (IP) on it’s Ethernet interfaces?
a) SNAP
b) ARPA
c) NOVELL-ETHER
d) DARPA
e) Ethernet_802.3
Answer
b) ARPA
SNAP is the default encapsulation for a token ring interface NOVELL-ETHER is the default encapsulation for a ipx interface.
3. [CxNx] What will be the correct command on a Cisco router to set the IP address of an interface assuming you are at the "router(config-if)#" prompt?
a) ip address 1.1.1.1 255.255.255.0
b) ip address 1.1.1.1
c) ip 1.1.1.1
d) ip 1.1.1.1 255.255.255.0
e) none of the above
Answer
a) ip address 1.1.1.1 255.255.255.0
If you are not in the configuration mode, the ip address can be set by using the setup mode.
Configuring interface Ethernet0/0:
Is this interface in use? [yes]:
Configure IP on this interface? [yes]:
IP address for this interface [10.10.10.1]: 10.10.10.1
Number of bits in subnet field [16]: 16
Class A network is 10.0.0.0, 16 subnet bits; mask is /24
Take note when using the setup mode the mask is configured using the number of subnet bits.
4. [CxNx] Which commands will display the IP addresses of all interfaces on a Cisco Router? (Choose all that apply)
a) show ip route
b) show ip address
c) show ip interface
d) show interface
e) display ip addresses
Answer
c) show ip interface
d) show interface
Examples of each of these commands are shown below:
Router_A#sh int e0/0
Ethernet0/0 is up, line protocol is up
Hardware is AmdP2, address is
0010.7b15.bd41
(bia 0010.7b15.bd41)
Internet address is 10.10.10.1/24
MTU 1500 bytes, BW 10000 Kbit,
DLY 1000 usec,
rely 255/255, load 1/255
Encapsulation ARPA, loopback not set,
keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output 00:00:06,
output hang never
Last clearing of "show interface"
counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops;
input queue 0/75,
0 drops
5 minute input rate 0 bits/sec,
0 packets/sec
5 minute output rate 0 bits/sec,
0 packets/sec
0 packets input, 0 bytes,
0 no buffer
Received 0 broadcasts, 0 runts,
0 giants,
0 throttles, 0 input errors, 0 CRC,
0 frame, 0 overrun, 0 ignored,
0 abort
0 input packets with dribble
condition detected
127 packets output, 11802 bytes,
0 underruns
0 output errors, 0 collisions,
2 interface resets
0 babbles, 0 late collision,
0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output
buffers swapped out
Router_A#sh ip int e0/0
Ethernet0/0 is up, line protocol is up
Internet address is 10.10.10.1/24
Broadcast address is 255.255.255.255
Address determined by
non-volatile memory
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is enabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is enabled
IP fast switching on the same
interface is disabled
IP multicast fast switching is enabled
Router Discovery is disabled
IP output packet accounting is disabled
IP access violation accounting is
disabled
TCP/IP header compression is disabled
Probe proxy name replies are disabled
Gateway Discovery is disabled
Policy routing is disabled
Network address translation is disabled
5. [CxNx] Which of the following commands will display the contents of the ARP cache of your Cisco router?
a) show ip arp cache
b) show ip route
c) show ip arp
d) show arp
e) there is no way to display the ARP cache
Answer
c) show ip arp
Example:
Router_A#sh ip arp
Protocol Address Age(min) Hardware Address Type Interface
Internet 1.1.1.2 - 0010.7b15.bd50 ARPA FastEthernet1/0
Internet 10.10.10.1 - 0010.7b15.bd41 ARPA Ethernet0/0
6. [CxNx] Reverse Address Resolution Protocol (RARP) is the process:
a) Where an IP host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.
b) Where an IP host resolves it’s MAC address by broadcasting to the local network it’s IP address.
c) Where an IP host tries to resolve the MAC address of a destination by sending a network broadcast. The destination responds to the broadcast with it’s MAC address.
d) Where an IP host resolves a destination IP address by sending a broadcast on the local network and the destination host responds with it’s IP address.
e)There is no such process.
Answer
a) Where an IP host resolves it’s IP address by broadcasting it’s MAC address to the network and a BOOTP server assigns it an IP address.
Choice C describes Address Resolution Protocol (ARP). A host never has to resolve it’s own MAC address. The MAC address is burned into the Network Interface card. When the host is booted the MAC address will be loaded into memory.
7. [OxNx] Which of the following applications requires the connection-oriented layer four protocol, TCP? (Choose all that apply)
a) Telnet
b) FTP
c) TFTP
d) SNMP
e) none of the above
Answer
a) Telnet
b) FTP
TFTP and SNMP use layer 4 UDP.
8. [RxNx] Which of the following are link state Routing Protocols.
(Choose all that apply.)
a) IP
b) OSPF
c) RIP
d) EIGRP
e) IS-IS
Answer
b) OSPF
e) IS-IS
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