A systems administrator is troubleshooting a connectivity issue between a new application server and a database server. The application server can successfully ping the database server by its IP address, but the application is unable to establish a connection. The administrator suspects a firewall is blocking the required TCP port. Which of the following commands would be the MOST effective to run from the application server to test connectivity to the specific port on the database server?
The correct command is telnet <db_server_ip> <port>. This command attempts to establish a connection on a specific TCP port on the destination host. A successful connection (e.g., a blank screen or connection message) indicates the port is open and reachable. A connection timeout or refusal message suggests the port is closed or blocked by a firewall. tracert is used to trace the network path to a destination and is not suitable for checking port-specific connectivity. netstat -r displays the local routing table and does not test remote port connectivity. nslookup is used for DNS queries; since the IP address is being used successfully for ping, DNS is not the issue.
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What is the purpose of the telnet command in troubleshooting network connectivity?
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What happens if the telnet command fails to connect to a specific port?
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Why is `tracert` not suitable for testing specific port connectivity?