certmaster Supporting IPv4 and IPv6 Networks Flashcards
A helpdesk operator is troubleshooting communications between devices in the same location, but one is having issues communicating with the others. Which of the following will have issues?
A.Host A: IP: 192.168.1.10, Mask: 255.255.255.0
B.Host B: IP: 192.168.1.11, Mask: 255.255.255.0
C.Host C: IP: 192.168.1.21, Mask: 255.255.0.0
D.Host D: IP: 192.168.0.10, Mask: 255.255.255.0
D
Host D will not be able to communicate with the others. Host C cannot contact host D, as it thinks that host D is on the same local network. In fact, Host C needs to route messages for 192.168.0.0/24 via the default gateway.
Host A and B have the same subnet mask as each other. Host C will be able to use ARP messaging and receive replies.
Host B has the same subnet mask as Host A. Host C will be able to use ARP messaging and receive replies.
Host C will be able to use ARP messaging and receive replies to hosts A and B.
A network administrator is diagnosing a suspected problem with local addressing and packet delivery. Which of the following commands would the administrator use to add an entry to the ARP cache?
A.arp -a
B.arp -d
C.arp -g
D.arp -s
D
The arp -s IPAddress MACAddress adds an entry to the ARP cache. Under Windows, the network administrator needs to enter the MACAddress with hyphens between each hex byte.
The arp -a shows the ARP cache contents. The network administrator can use this with IPAddress to view the ARP cache for the specified interface only. The ARP cache will not necessarily contain the MAC addresses of every host on the local segment.
The arp -d * deletes all entries in the ARP cache, and the network administrator can also use it with an IPAddress to delete a single entry.
The arp -g command is the same as arp -a.
A helpdesk technician is troubleshooting issues on a Windows client. Which command does the technician use to clear the current IP address so that a new one may be obtained?
A.ipconfig /flushdns
B.ipconfig /all
C.ipconfig /release
D.ipconfig /renew
C
The ipconfig /release interface command releases the IP address obtained from a Dynamic Host Configuration Protocol (DHCP) server so that the interface(s) will no longer have an IP address.
The ipconfig /flushdns command clears the Domain Name System (DNS) resolver cache. The ipconfig command is still widely used for basic configuration reporting and support tasks.
The ipconfig /all command displays complete Transmission Control Protocol/Internet Protocol (TCP/IP) configuration parameters for each interface, including the DHCP.
The ipconfig /renew interface command forces a DHCP client to renew the lease it has for an IP address. The system typically performs this after the ipconfig /release tries to obtain a different dynamic IP address.
A network administrator is setting up router advertisements through Neighbor Discovery protocol on an IPv6 network. Which of the following is NOT one of the main functions?
A.Error messaging
B.Address autoconfiguration
C.Prefix discovery
D.Local address resolution
A
Error messaging is one of the new features of Internet Control Message Protocol version 6 (ICMPv6). One change is the introduction of a Packet Too Big class of error. Under IPv6, routers are no longer responsible for packet fragmentation and reassembly.
Address autoconfiguration enables a host to configure IPv6 addresses for its interfaces automatically and detect whether an address is already in use on the local network.
Prefix discovery enables a host to discover the known network prefixes allocated to the local segment. This facilitates next-hop determination.
Local address resolution allows a host to discover other nodes and routers on the local network (neighbors).
A Linux systems administrator wants to interface correctly with modern network configuration manager packages. Which of the following would be best to accomplish this?
A.iproute2
B.net-tools
C.ifconfig
D.ipconfig
A
The iproute2 package can interface correctly with modern network configuration manager packages. Running the ip addr command performs the basic reporting functionality of ifconfig that shows the current address configuration.
The iproute2 package has replaced Net-tools. Keep in mind these changes are not persistent and apply only to the running configuration unless run as part of a startup script.
The ifconfig command is part of the legacy net-tools package. Most modern Linux distributions deprecate the use of these commands.
Windows systems use the ipconfig command. PowerShell replaced this with the NetIPaddress modules.
A security engineer is analyzing IPv6 packets. Which of the following header fields is for quality of service?
A.Traffic class
B.Payload length
C.Hop limit
D.Flow label
D
The flow label is for quality of service (QoS) management, such as for real-time streams. The security engineer sets the flow label to 0 for packets not part of any delivery sequence or structure.
The Traffic Class field describes the packet’s priority.
Payload length indicates the length of the packet payload, up to a maximum of 64 KB. If the payload is larger than that, then this field is 0, and the security engineer will establish a special Jumbo Payload (4 GB) option.
Hop limit replaces the time to live (TTL) field in IPv4 but performs the same function.
A security technician is analyzing packets on an IPv6 network. Which of the following headers would indicate a multicast packet? (Select all that apply.)
A.011
B.1111 1111
C.ff
D.fe80
B, C
The first 8 bits indicate that the address is within the multicast scope 1111 1111. A multicast address sends a packet from a single source to multiple network interfaces.
Another way to indicate a multicast IPv6 address is ff, which is the same as 1111 1111. Unlike IPv4, IPv6 routers must support multicast.
Not being 011 but rather 001, the first 3 bits would indicate that the address is within the global scope. The scope for globally unique unicast addressing occupies just 1/8th of the total address space.
Link local addresses start with a leading fe80.
A network technician is investigating a significant increase in network bandwidth usage impacting network performance. After running diagnostic commands on the network switch, the technician notices unusually high counters on IGMP messages through each switch port. Which of the following is most likely causing the increased bandwidth consumption and network slowdown?
A.IGMP snooping
B.Multicast transmissions
C.Host resolution issues
D.Duplicate IPs
B
At layer 2, if a switch is not multicast-aware, it treats multicast transmissions as broadcasts and floods them across all ports, consuming a lot of bandwidth and slowing down the network.
Internet Group Management Protocol (IGMP) snooping means the switch reads IGMP messages and can determine if the host on an access port, or one or more hosts in a Virtual Local Area Network (VLAN), have joined a multicast group.
When a technician successfully performs all connectivity tests by IP address but cannot ping by host name, this suggests a name resolution problem. However, this does not flood the network.
If Windows detects a duplicate IP address, it will display a warning and disable IP. Linux does not typically check for duplicate IP addresses.
A security technician is analyzing IPv6 traffic and looking at incomplete addresses. Which of the following is a correct IPv6 address?
A.2001:db8:abc:def0::1234
B.2001:db8::abc::def0:1234
C.2001:db8::abc:def0::1234
D.2001::db8:abc:def0::1234
A
The address 2001:db8:abc:def0::1234 is a correct address. The double colon (::) compression can only be used once in a given address.
The address 2001:db8::abc::def0:1234 is not correct since it uses double colon compression more than once. The hex notation can compress further using canonical notation.
The address 2001:db8::abc:def0::1234 is not correct since it uses double colon compression more than once. Where a double byte contains leading 0s, they can be ignored. In addition, a double colon place marker can replace one contiguous series of 0s.
The address 2001::db8:abc:def0::1234 is not correct since it uses double colon compression more than once. Keep in mind where IPv6 addresses are part of a URL, the IPv6 address must be contained within brackets.
A network technician is setting up IPv6 global addressing. Which of the following is NOT part of an IPv6 unicast address?
A.Starts with 001
B.Network ID
C.Starts with fe80
D.Subnet
C
Link local addresses start with a leading fe80, but global IPv6 addresses begin with 001.
The network technician allocates the next 45 bits after the 001, in a hierarchical manner, to regional registries, then to ISPs, and finally, to end-users.
The first 3 bits (001) indicate that the address is within the global scope. Most of the IPv6 address space is unused. The scope for globally unique unicast addressing occupies just 1/8th of the total address space. In hex, globally scoped unicast addresses will start with a 2 (0010) or 3 (0011).
The next 16 bits after the Network ID identify site-specific subnet addresses.
A consultant is visiting a new project and forgot to take the manual configurations off the computer from the last project. The client receives issues due to a disabled IP. What does the client most likely have?
A.Duplicate MACs
B.Duplicate IPs
C.Incorrect subnet mask
D.Interface status issues
B
If Windows detects a duplicate IP address, it will display a warning and disable the IP. Linux does not typically check for duplicate IP addresses.
Duplicate MAC addresses are unlikely to arise unless the network uses locally administered addressing.
If a subnet mask is incorrect, the host thinks it can receive communications. It misrouted the replies thinking that the hosts communicating with it are on a different subnet.
The administrator can isolate the issue to a single host and then rule out cable and transceiver issues at the physical layer. However, bear in mind that the data link configuration might not be working.
A helpdesk technician is setting up a new IP configuration for a new Ethernet adapter on a client using PowerShell. Which command should the technician use?
A.Set-NetIPAddress
B.New-NetIPAddress
C.netsh interface ip set address “Ethernet” dhcp
D.netsh interface ip set address “Ethernet” static 10.1.0.1 255.255.255.0 10.1.0.254
B
A new Ethernet adapter configuration can be applied using New-NetIPAddress in Powershell.
An existing Ethernet adapter can be modified using Set-NetIPAddress in PowerShell. In earlier Windows versions, “Local Area Connection” was the first adapter’s name, but recent versions just use the label “Ethernet.”
The netsh interface ip set address “Ethernet” dhcp is a way to configure an Ethernet adapter, but it uses the legacy command prompt instead of PowerShell.
The netsh interface ip set address “Ethernet” static 10.1.0.1 255.255.255.0 10.1.0.254 is a way to set a static IP for an Ethernet adapter, but it is also the legacy command instead of PowerShell.
A network administrator is diagnosing a suspected problem with local addressing and packet delivery. Which of the following commands would the administrator use to flush the ARP cache?
A.arp -a
B.arp -d
C.arp -g
D.arp -s
B
The arp -d * deletes all entries in the ARP cache, and the network administrator can also use it with an IPAddress to delete a single entry.
The arp -a shows the ARP cache contents. The network administrator can use this with IPAddress to view the ARP cache for the specified interface only. The ARP cache will not necessarily contain the MAC addresses of every host on the local segment.
The arp -g command is the same as arp -a.
The arp -s IPAddress MACAddress adds an entry to the ARP cache. Under Windows, the network administrator needs to enter the MACAddress with hyphens between each hex byte.
