Static routing is considered more secure than dynamic routing for several key reasons, primarily related to its predictable nature, manual configuration, and lower susceptibility to certain types of attacks and vulnerabilities.

Below are some of the reasons why static routing can be considered more secure:

1. Control and Predictability

• Manual Configuration: Static routes are manually configured by network administrators, which means they are not automatically learned through routing protocols. This gives administrators full control over the routing topology, reducing the risk of unwanted or malicious routes.
• Stability: Static routes do not change unless an administrator modifies them. This eliminates the possibility of unexpected routing table changes, which could result from misconfigurations or network attacks.

2. Smaller Attack Surface

• No Route Announcements: By not using dynamic routing protocols, networks that use static routing do not advertise or receive route advertisements. This reduces the attack surface, as attackers cannot exploit routing protocols to inject malicious routes or divert traffic.
• Immunity to Specific Attacks: Attacks that specifically target vulnerabilities in dynamic routing protocols, such as OSPF or BGP, do not affect networks that exclusively use static routing.

3. Simplicity and Transparency

• Audit Facility: Static routes are easy to document, audit, and verify, allowing network administrators to efficiently perform security reviews and ensure traffic flows exactly as expected.
• Less Complexity: By not relying on complex algorithms or the state of other routers in the network to make routing decisions, static routing eliminates a set of variables that could be exploited to compromise the network.

Considerations

Although static routing offers advantages in terms of security, it also has its limitations, such as lack of scalability in large networks and reliance on manual intervention for maintenance, which can lead to human errors.

Additionally, in situations where the network topology changes frequently, keeping static routes up to date may be impractical.

Therefore, in environments where security is a primary concern but some flexibility and automation is needed, a combination of static routing for critical paths and dynamic routing with additional security measures, such as routing protocol authentication and access control lists, to offer a balance between security, maintenance and flexibility.