These are some steps for resolving issues with DNS. A gateway is not required for LAN access so this cannot be the answer.
Solution 1: Check your Computer is correct or not for IP Address
Solution 2: Flush and Reset a client resolver cache and Renew DNS client registration Solution 3: Edit DNS Lookup Host file entry
https://morgantechspace.com/2014/03/can-ping-by-ip-address-but-not-by-machine-name.html#

The administrator should use an IP KVM to access the server's console remotely for bare-metal maintenance. An IP KVM stands for Internet Protocol Keyboard Video Mouse, which is a device that allows remote control of a server's keyboard, video, and mouse over a network connection, such as LAN or Internet. An IP KVM enables an administrator to perform tasks such as BIOS configuration, boot sequence selection, operating system installation, etc., without being physically present at the server location.
The other options are not suitable for bare-metal maintenance because they require either physical access to the server (a crash cart) or an operating system running on the server (VNC, RDP, SSH). A crash cart is a mobile unit that contains a monitor, keyboard, mouse, and cables that can be plugged into a server for direct access to its console. VNC stands for Virtual Network Computing, which is a software that allows remote desktop sharing and control over a network connection using a graphical user interface (GUI). RDP stands for Remote Desktop Protocol, which is a protocol that allows remote desktop access and control over a network connection using a GUI or command-line interface (CLI). SSH stands for Secure Shell, which is a protocol that allows secure remote login and command execution over a network connection using a CLI.

These are two measures that should be taken when a data breach occurs. A data breach is an unauthorized or illegal access to confidential or sensitive data by an internal or external actor. A data breach can result in financial losses, reputational damage, legal liabilities, and regulatory penalties for the affected organization. Disclosing the incident is a measure that involves informing the relevant stakeholders, such as customers, employees, partners, regulators, and law enforcement, about the nature, scope, and impact of the data breach. Disclosing the incident can help to mitigate the negative consequences of the data breach, comply with legal obligations, and restore trust and confidence. Identifying the exploited vulnerability is a measure that involves investigating and analyzing the root cause and source of the data breach. Identifying the exploited vulnerability can help to prevent further data loss, remediate the security gaps, and improve the security posture of the organization. Restoring the data from backup is a measure that involves recovering the lost or corrupted data from a secondary storage device or location. However, this does not address the underlying issue of how the data breach occurred or prevent future breaches. Disabling unnecessary ports is a measure that involves closing or blocking network communication endpoints that are not required for legitimate purposes. However, this does not address how the data breach occurred or what vulnerability was exploited. Running an antivirus scan is a measure that involves detecting and removing malicious software from a system or network. However, this does not address how the data breach occurred or what vulnerability was exploited. Moving the data to a different location is a measure that involves transferring the data to another storage device or location that may be more secure or less accessible. However, this does not address how the data breach occurred or what vulnerability was exploited. Reference: https://www.howtogeek.com/428483/what-is-end-to-end-encryption-and-why-does-it-matter/ https://www.howtogeek.com/202794/what-is-the-difference-between-127.0.0.1-and-0.0.0.0/ https://www.howtogeek.com/443611/how-to-encrypt-your-macs-system-drive-removable-devices-and-individual-files/

The subnet mask is most likely containing an error that prevents the application server from communicating with the newly installed database server. The subnet mask is a binary number that defines how many bits of an IP address are used for the network portion and how many bits are used for the host portion. The subnet mask determines which devices belong to the same network or subnet and can communicate directly with each other without routing or switching devices. The subnet mask of the database server is 255.255.O.O, which means that all 32 bits of its IP address are used for the network portion and none for the host portion, which is invalid and makes it unreachable by any other device on any network or subnet. The subnet mask of the application server is 255.O.O.O, which means that only 8 bits of its IP address are used for the network portion and 24 bits are used for the host portion, which is also uncommon and makes it incompatible with most networks or subnets. References: [CompTIA Server+ Certification Exam Objectives], Domain 4.0: Networking, Objective 4.1: Given a scenario, configure network settings for servers.

The BIOS (Basic Input/Output System) is a firmware that controls the initialization and booting of a server. It also provides settings for the CPU, such as speed, voltage, and temperature. Updating the BIOS can improve the performance and compatibility of the CPU and other hardware components. Verified References: [BIOS],
[CPU]