Communicating Between Networks Exam

Where are IPv4 address to Layer 2 Ethernet address mappings maintained on host computer?

ARP cache

What are two drawbacks to ARP?

ARP requests are broadcasts. Excessive broadcasts consume network resources (bandwidth) ARP poisoning

show ip arp (router) arp -a (windows)

Displays ARP table

Best effort

IP is inherently (permanent) unreliable because packet delivery is not guaranteed.

A computer can access devices on same network but cannot access devices on other networks. What is the probable cause of this problem?

Incorrect default gateway

Which command are used to set up secure access to router through connection to console interface?

Line console 0

Which parameter does router use to choose path to destination when there are multiple routes available?

Lower metric value associated with destination network

NAT is not needed for IPv6. Why?

Number of available IPv6 addresses is extremely large. All hosts and users can get public IPv6 addresses. No translation is necessary

What are two potential network problems that can result from ARP operation?

On large networks with low bandwidth, multiple ARP broadcasts could cause data communication delays. Network attackers could manipulate MAC address and IP address mappings in ARP messages with the intent of intercepting network traffic.

Two jobs of router

Packet forwarding Packet selection

Secure remote Telnet/SSH access

Router(config-line)# line vty 0 4 Router(config-line)# password password Router(config-line)# login Router(config-line)# transport input {ssh | telnet}

Running-config mode

Stored in Random Access Memory (RAM). Reflects current configuration Affects operation of Cisco device immediately

The command "ip default-gateway 192.168.1.1" is issued on a switch. What is the result?

Switch can be managed remotely from host on another network.

Connectless

There is no connection with destination established before sending data packets.

Which field in IPv4 header is used to prevent packet from traversing network and endlessly limit lifetime of packet?

Time to live

What does ARP force all ethernet NICs to process and ARP request?

When it's broadcast frame (FF-FF-FF-FF-FF-FF)

R1(config-if)# mode

ip address 192.168.4.4 255.255.255.0

R1(config-line)# mode

login

What routing table entry has next hop address associated with destination network?

remote routes

What are two services provided by OSI (Open Systems Interconnection) network layer?

routing packets toward destination encapsulating PDUs from transport layer

What are two functions of NVRAM?

to retain (keep) contents when power is removed to store startup configuration file

Which term describes field in IPv4 packet header that contains 4-bit binary value set to 0100?

version

Purpose of configuring switch with default gateway address

Default gateway address is used to forward data originating from switch to remote networks

The IP protocol handles missing and out of sequence packets

False

The default gateway is incorrectly configured on host. What is the result?

Host will not be able to communicate with hosts on remote networks

Perform POST and load bootstrap program.

Phase 1

SSH

Remote access method that uses encryption

What information does pinging loopback address provide?

TCP/IP stack on device is working correctly

What is the aim of ARP spoofing attack?

To associate IP addresses to wrong MAC address

Line Configuration Mode

Used to configure console, SSH, Telnet, or AUX access.

User EXEC mode

Allows only limited number of basic monitoring commands but does not allow execution of any commands that might change configuration of device referred to as "view-only" mode.

ARP poisoning

Attack that spoofs (trick) legitimate user's MAC address and intercept traffic

What does command "arp-d*" do when issued on PC?

Clears ARP cache

What happens when transport input ssh command is entered on switch vty lines?

Communication between switch and remote users is encrypted.

What are some characteristics of IP protocol

Connectless Best effort Media independent

What information in ethernet frame header is examined by switch to make forwarding decision What important information is examined in Ethernet frame header by Layer 2 device in order to forward data onward?

Destination MAC address

When will a switch flood frame out of every port?

Destination MAC address FF-FF-FF-FF-FF-FF Frame's destination MAC address is not switch's CAM table

Under which two circumstances will a switch flood a frame out of every port except the port that the frame was received on?

Destination address is unknown to switch Frame has broadcast address as destination address

Name the field in IPv4 packet header used to determine priority of packet?

Differentiated services

show ip interfaces

Displays IPv4 statistics for all interfaces on router

show ipv6 interface

Displays IPv6 statistics for all interfaces on router

show ip interface brief show ipv6 interface brief

Displays all interfaces, their IP addresses, and their current status

show ip route show ipv6 route

Displays contents of IP routing tables stored in RAM

show interfaces

Displays statistics for all interfaces on device. Only displays IPv4 addressing information

What is one advantage that IPv6 simplified header offers over IPv4?

Efficient packet handling

How is ARP utilized by hosts on LAN to send traffic to remote networks?

Enables them to discover MAC address of default gateway.

A new network administrator has been asked to enter banner message on Cisco device. What is the fastest way a network administrator could test whether banner is properly configured?

Exit privileged EXEC mode and press Enter .

When transporting data from real-time applications, such as streaming audio and video, which field in IPv6 header can be used to inform routers and switches to maintain same path for packets in same conversation?

Flow label

Physical layer

Lowest, or first, layer of OSI model. Generate and detect signals so as to transmit and receive data over network medium. Set data transmission rate and monitor data error rates, but do not provide error correction.

Which two types of IPv6 messages are used in place of ARP for address resolution?

Neighbor solicitation Neighbor Advertisement

Encapsulation

Network layer encapsulates protocol data unit (PDU) from transport layer into packet. Adds IP header information, such as IP address of source (sending) and destination (receiving) hosts. Performed by source of IP packet.

Media independent

Operation is independent of medium (i.e., copper, fiber-optic, or wireless) carrying data.

Locate and load Cisco IOS software.

Phase 2

Locate and load startup configuration file or enter setup mode.

Phase 3

Segmentation

Process of dividing stream of data into smaller units of transmissions over network

Console

Provides out of band access

Network layer (OSI layer 3)

Provides services to allow end devices to exchange data across networks

Provide legal notification

Router(config)# banner motd delimiter message delimiter

Save configuration

Router(config)# end Router# copy running-config startup-config

Secure user EXEC mode

Router(config)# line console 0 Router(config-line)# password password Router(config-line)# login

Secure privileged EXEC mode

Router(config)#enable secret password

Secure all passwords in config line

Router(config-line)# exit Router(config)# service password-encryption

Which term describes field in IPv4 packet header used to limit lifetime of packet?

TTL

What property of ARP causes NICs receiving ARP request to pass data portion of Ethernet frame to ARP process?

Type field 0x806 appears in header of Ethernet frame.

Interface Configuration Mode

Used to configure switch port or router network interface.

Function of address resolution protocol?

Used to determine MAC address of any host of LAN

global configuration mode

User can enter different subconfiguration modes. Each of these modes allows configuration of particular part or function of IOS device