Network+ Chapter 10 Command-Line Tools

arp

- used to display *MAC address to IP address mappings*

*SECTION 10.2*

*UNIX Commands*

*SECTION 10.1*

*Windows Commands*

Windows ipconfig /all Command

- *additional output* from this command, not shown in the output of the ipconfig command - the *MAC address* (labeled as the physical address) for each NIC and the *DNS server's IP address*

Comparing Output from the UNIX dig and nslookup Commands

- *dig* command *offers more information* than the nslookup command - *A* in the *QUESTION SECTION* output of the dig command identifies the *DNS record type* - used by many UNIX administrators as simply an alternate way of resolving FQDNs to IP addresses

route

- *not used to display* a host's IP *routing table* - used to *modify a UNIX host's IP routing table* - to *add or delete a route* from a UNIX host's routing table

Sample Output from the Windows ipconfig Command

- PC contains an Ethernet and a wireless network interface card (NIC) - conclude that one of the NICs has an IP address of 172.16.202.129, while the other NIC has an IP address of 172.16.202.128 - share a common default gateway of 172.16.202.2

PathPing

- Windows tool *combines features* of *Ping and Tracert* over a period of time - used with IPv4 and IPv6 - shows the *amount of packet loss at any given router* so you can identify the routers that might be causing in the path

Sample Output from the Windows nbtstat -a Command

- allows you to view the *NetBIOS table* of a *remote PC* - the *Node IpAddress parameter* shows the IP address of the PC issuing the nbtstat command - the *MAC Address parameter* shows the MAC address of the remote PC

route

- can display a PC's current *IP routing table* - use the command to *add or delete entries* to or from that routing table

Sample Output from the UNIX netstat Command

- command issued by itself produces output that details each current session

Sample Output from the Windows netstat Command

- command issued without any options lists *source and destination IP addresses* and *port numbers* for all *IP-based sessions*

Sample Output from the Windows ping Command

- command specifying only the target_name parameter sends *four ICMP echo messages to the specified target* - notice that none of the packets were dropped

ipconfig

- command to *display IP address configuration parameters* on a Windows PC - use the command to *release and renew a DHCP lease*, which is often useful when troubleshooting

Adding a Static Route with the UNIX route Command

- command to add a static route to a UNIX host s routing table - a route to 10.1.2.0/24 with a next-hop gateway of 192.168.1.1 is being added - netstat -r command issued after the route command to confirm the insertion of the 10.1.2.0/24 route into the UNIX host s routing table

nslookup

- command to resolve an *FQDN to an IP address* - help you to determine *whether a DNS record is correct* and to verify that your *DNS server is operating*

netstat

- display various information about current connections - information includes source and destination IP addresses and port numbers - display protocol statistics

nbtstat

- displays *NetBIOS information* for IP-based networks - nbt prefix refers to *NetBIOS over TCP/IP*, which is called NBT or NetBT - display a listing of NetBIOS *device names learned* by a Windows PC

Windows route print Command

- displays the *contents* of a PC's *routing table* - output identifies a *listing of the PC's interfaces*, along with IPv4 routes and IPv6 routes - notice that there is a *persistent route* (a route entry that survives a reboot) to act as a *default gateway* for the PC

tracert

- if the ping were *unsuccessful*, or if the round-trip response *times seem too long*, the tracert command might *help isolate the issue* - pings every router hop from the source to the destination and *reports the round-trip time for each router hop* - in *many cases*, a router does not respond to a tracert because it has been *configured not to respond to ICMP messages* - failed response does not always indicate a router-configuration issue or a bad link between two routers

Sample Output from a Sample UNIX man Command

- if you want *detailed information about the arp* command, you can *enter man arp* to produce the output shown

Sample Output from the Windows netstat -b Command

- might notice an *open connection* using a specific port and be *unsure* what application opened that connection - command shows *which application opened a specific connection*

ping

- most typically used to test network reachability to a specified destination - sends continuous pings, as opposed to the Windows default of only four pings

Sample Output from the Windows route add Command

- route can be added by using this command - shows and confirms the addition of a route pointing to the 10.2.1.0 255.255.255.0 network, with a next-hop route (gateway) of 192.168.1.1

arp

- see what a *Layer 2 MAC address* corresponds *to* as a known *Layer 3 IP address* - use to *statically add a MAC address* to IP address mapping to a PC's ARP MAC address lookup table (ARP cache)

Sample Output from a Successful Windows tracert Command

- shows a successful trace from a PC to a destination FQDN of pearsonitcertification.com - output still *helps identify any slow links* interconnecting routers along the path from the source to the destination

Sample Output from the UNIX ping -c Command

- shows output from a ping command limited to sending only five ICMP echo packets

Sample Output from the Windows ipconfig /release Command

- suspect that IP addressing might be an issue, you can release the PC's current DHCP lease with the ipconfig /release command

netstat

- to display various information about *IP-based connections* on a PC - view information about *current sessions* - can also display *protocol statistics* (troubleshooting purposes) - might *issue* the command and see that your PC has *sessions open to an unknown host* on the Internet

dig and nslookup

- use for *FQDN-to-IP* address resolution - entirely a *command-line command* - *lacks* the *interactive mode*

Sample Output from the Windows nbtstat -r Command

- verify that a PC is successfully *resolving NetBIOS names*, either by using a *broadcast or* from a *WINS server*

Adding and Confirming a Static ARP Entry with the UNIX arp Command

- want to add an *entry* in your UNIX host's *ARP cache* for an IP address of *192.168.1.32* - MAC address of that device is *11:22:33:44:55:66* - device is available off of *interface en0* - enter the arp command with the *-s option* to add a *static* ARP entry - example then confirms the entry has been made by issuing the arp -a command

Q: Refer to the exhibit. Examine the output shown. What is the address that information is sent to if it is determined that the remote address is on a different subnet?

192.168.1.1 The default gateway shown in the exhibit is 192.168.1.1. This is the destination of traffic for a remote subnet. 192.168.1.19 is the local IP of the system. 255.255.255.255 would be used for a broadcast, and 8.8.8.8 is the primary DNS server.

Q: Refer to the exhibit. What is the output shown?

The *ARP cache* information This output shows the ARP cache information viewed by *arp -a* in Windows. The NetBIOS name cache, routing table, and NAT table all show very different information.

Q: Which of the following is a Microsoft Windows® command that displays what Layer 2 MAC address corresponds to a Layer 3 IP address?

arp The "arp" command can be used to see what a Layer 2 MAC address corresponds to a known Layer 3 IP address. Additionally, the "arp" command can be used to statically add a MAC address to IP address mapping into a PC's ARP table (sometimes called the ARP cache).

Q: Refer to the exhibit. What command produced the output shown on your Windows workstation?

arp -a This output is from the use of arp -a.

Q: Which of the following UNIX commands can be used to configure the IP address of a UNIX host's Ethernet interface?

ifconfig Issued by itself, the "ifconfig" command displays a UNIX host's interfaces along with configuration information about those interfaces, including: MAC address, maximum transmission unit (MTU), IPv4 address, and IPv6 address information.

Q: What tool would you use to release a DHCP address on a Windows system?

ipconfig The ipconfig tool is used to release and renew DHCP information. No other tool here can accomplish this.

Parameters for the Windows arp Command

switches (for example, -s, -d, and -a) and arguments (for example, inet_addr and if_addr)

Windows ping Command Indicating an Unreachable Destination

- if the specified target address is *unreachable*, output from the ping command indicates that the *target cannot be reached*

traceroute for IPv6

- may be done by using traceroute destination-IPv6-address, traceroute6 destination-IPv6-address, traceroute -6 destination-IPv6-address, or some variant specific to the vendor and product being used

host

- offers a variety of options - FQDN-to-IP address resolution

Sample Output from the Windows arp -a Command

- output shows what *MAC addresses* have been *learned* for the listed IP addresses - *dynamically learned* addresses have dynamic listed in the Type column - *statically configured* addresses are listed with static in the Type column - *static* ARP entries tend to be *more problematic* than dynamic entries

ping with IPv6

- ping can natively work to test connectivity using IPv6 when an IPv6 destination address is part of the ping command - *ping -6 IPv6-destination-address, ping6 IPv6-destination-address*, or some variant specific to that operating system may be available for testing IPv6 connectivity

ping

- use it to *check IP connectivity* between two network devices - multiple platforms (for example, routers, switches, and hosts) support - uses *ICMP (Layer 4 protocol)* - *PC* sends an *ICMP echo message* to the specified destination host - *host* responds with an *ICMP echo reply* message - indicate that a destination host is *unreachable*, that an ICMP echo *timed out*, or that a Time To Live (TTL) value has *expired*

Deleting and Confirming the Deletion of a Static ARP Entry with the UNIX arp Command

- want to delete the entry you just added - the *-d option* of the arp command can *remove an entry* from a host's ARP cache - output then confirms that the entry was removed

Sample Output from the Windows nslookup *Noninteractive* Command

- you issue the nslookup command followed by an FQDN to display the *IP address corresponding to the FQDN*

Sample Output from the Windows route delete Command

- you want to remove one of the route entries for the 10.0.0.0 255.0.0.0 network - shows how one of the two entries (specifically, the entry pointing to 192.168.1.11) can be removed from the routing table - notice from the output that after the route delete 10.0.0.0 mask 255.0.0.0 192.168.1.11 command is issued, the route no longer appears in the routing table

Q: Refer to the exhibit. What command produced the output shown on your Windows workstation?

nbtstat When troubleshooting, it often helps to know the IP address of a known NetBIOS name. You can view a *PC's NetBIOS name cache*, which lists this information, with the *nbtstat -c* command.

Q: Which of the following is a Microsoft Windows® command that can display a listing of NetBIOS device names learned by a PC?

nbtstat The "nbtstat" command displays NetBIOS information for IP-based networks. The nbt prefix of the "nbtstat" command refers to NetBIOS over TCP/IP, which is called NBT, or NetBT. This command can, for example, *display a listing of NetBIOS device names learned by a Microsoft Windows® PC*.

Q: What command enables you to refresh DHCP lease information?

ipconfig You can use the ipconfig command to release and refresh IP address information learned from a DHCP server.

Q: What command enables you to view the DNS settings for the device?

ipconfig /all The ipconfig /all command enables you to see the most information, including DNS information.

tracert with IPv6

- *IPv6 path* through a network can be *verified with tracert* for IPv6 - may be done by using tracert destination-IPv6-address, tracert6 destination-IPv6-address, or tracert -6 destination-IPv6-address

Man Pages

- benefits of UNIX is its *extensive syntax reference* in the form of *manual pages*

Sample Output from the UNIX netstat -r Command

- can also be used to view the IP routing table of a UNIX host

traceroute

- can help isolate which router hop along the path from a source device to a destination device is having issues - can better determine which network segment might be causing excessive delay because of congestion

Sample Output from the Windows nslookup *Interactive* Command

- command is entered, after which you enter command parameters from the *> prompt* - notice that entering a question mark (?) displays a help screen that shows command options - entering *quit exits* you from interactive mode.

Configuring and Verifying the Configuration of an Interface's IP Address with the UNIX ifconfig Command

- configure interface en0 with an IP address of 192.168.1.26 and a subnet mask of 255.255.255.0, you could issue the command ifconfig en0 inet 192.168.1.26 netmask 255.255.255.0

ifconfig

- displays a UNIX host's interfaces along with configuration information about those interfaces, including MAC address, maximum transmission unit (MTU), IPv4 address, and IPv6 address information - also configure interface parameters

Sample Output from an Unsuccessful Windows tracert Command

- first-hop router (192.168.1.1) responded; however, the router beyond that did not respond - might focus your attention to the interconnection between those two routers

Sample Output from the Windows nbtstat -c Command

- helps to know the *IP address of a known NetBIOS name* - view a PC's NetBIOS *name cache*, which lists this information

Q: Refer to the exhibit. What command produced the output shown on your Windows workstation?

ipconfig /all This output was produced by ipconfig /all. ipconfig without the all keyword does not produce such verbose output.

Q: Which of the following UNIX commands can be used to invoke a UNIX syntax reference?

man One of the benefits of UNIX is its extensive syntax reference in the form of "manual pages," commonly referred to as "man pages." These man pages can be invoked with the *"man" command, followed by the command for which you wish to view a syntax reference.*

Q: Which of the following is a Microsoft Windows® command that can display a listing of the source and destination IP address for existing sessions on a PC?

netstat The "netstat" command can be used to display a variety of information about IP-based connections on a PC. For example, you can view *information about current sessions, including source and destination IP addresses* and port numbers. You can also display protocol statistics.

Q: Refer to the exhibit. What command produced the output shown on your Windows workstation?

nslookup

Q: While more than one of the following Microsoft Windows® commands can be used to resolve a fully-qualified domain name (FQDN) to an IP address, identify the command whose primary purpose is to resolve a FQDN to an IP address (for example, to determine if a Domain Name System (DNS) record is correct).

nslookup The "nslookup" command can be used to resolve a fully-qualified domain name (FQDN) to an IP address. This can, as a couple of examples, help you determine if a DNS record is correct, and verify your DNS server is operating.

Q: Which of the following UNIX commands is primarily used to resolve a fully-qualified domain name (FQDN) to an IP address and can operate in an interactive mode (that is, you enter this command, receive a prompt, and can then give additional commands)?

nslookup The Microsoft Windows® "nslookup" command is used to resolve a given FQDN to its IP address. UNIX has a similar "nslookup" command, which can also be used for FQDN to IP address resolution.

Q: What command enables you to verify DNS information and functionality?

nslookup The best command for this is nslookup. This tool is used specifically for the verification of DNS settings and results.

Q: Refer to the exhibit. What command produced the output shown on your Windows workstation?

ping This output shows the ping command output.

Q: Which tool enables you to test basic connectivity to a remote system?

ping ping is used to test basic connectivity.

Q: Which of the following Microsoft Windows® commands can be used to manipulate a PC's forwarding table?

route The "route" command can display a PC's current IP routing table. Additionally, the "route" command can be used to add or delete entries to or from that routing table.