Explanation
iperf is a tool that can measure the bandwidth and quality of a network link by generating and transferring TCP or UDP data streams. iperf can report the maximum achievable throughput, packet loss, jitter, and other statistics for a given link. iperf can be used to test both the uplink and downlink performance of a network link by running it on two endpoints and specifying the direction and duration of the test. iperf can help the engineer verify that the new fiber uplink meets the throughput requirements for the office network.
tcpdump is a tool that can capture and analyze network traffic by filtering and displaying packets based on various criteria. tcpdump can help the engineer troubleshoot network problems, monitor network activity, and inspect packet contents, but it cannot measure the throughput or quality of a network link.
ping is a tool that can test the reachability and latency of a network host by sending and receiving ICMP echo packets. ping can help the engineer check if the new fiber uplink is connected and responsive, and how long it takes for packets to travel between the endpoints, but it cannot measure the throughput or quality of a network link.
netstat is a tool that can display information about the network connections, routing tables, interfaces, and protocols on a network host. netstat can help the engineer view the status and details of the network connections using the new fiber uplink, but it cannot measure the throughput or quality of a network link.
References
iperf - The ultimate speed test tool for TCP, UDP and SCTP
How to use iperf to test local network LAN speed in Windows 10
How to Test Network Performance Between Two Linux Servers
What is tcpdump?
8 Common Network Utilities Explained
Monitoring Your Network: ping, netstat, tcpdump, and Ethereal
Netstat vs. Nmap vs. Netcat: Understanding the Differences

A broadcast storm Traffic that is recirculated and amplified by loops in a switching topology, causing network slowdowns and crashing switches.

The error message "Ping request could not find host www.google.com" indicates that the network engineer's PC cannot resolve the hostname www.google.com to its corresponding IP address. This means that there is a problem with the DNS (Domain Name System) service, which is responsible for translating hostnames to IP addresses and vice versa. The DNS service can be provided by internal or external name servers, depending on the network configuration.
The next step the engineer should take is to ping the internal name server functionality, which means to test if the PC can communicate with the name server that is configured in its network settings, and if the name server can resolve internal hostnames, such as those of the company's servers or devices. To do this, the engineer can use the following commands:
* To find out the IP address of the name server, use ipconfig /all and look for the DNS Servers entry.
* To ping the name server, use ping <name server IP address> and check if the packets are sent and received successfully.
* To test the name resolution, use nslookup <internal hostname> and check if the name server returns the correct IP address.
If the ping or the nslookup commands fail, it means that the internal name server is not working properly, and the engineer should troubleshoot the name server configuration or connectivity. If the ping and the nslookup commands succeed, it means that the internal name server is working properly, but there is a problem with the external name resolution, and the engineer should check the internet firewall logs for blocked DNS traffic, or test the website from outside the company.
References Windows 10 can't resolve hostnames - ping with IP works but not with hostnamePing request could not find host xyz.local.
Please check the name and try againDNS problem, nslookup works, ping doesn't