CREST Practitioner Security Analyst (CPSA) Practice

What value is typically assigned as the TTL for Linux devices?

1. 64

2. 128

3. 255

4. 32

The correct answer is: 64

In the context of Linux devices, the Time to Live (TTL) value is generally set to 64 by default. TTL is a mechanism used to limit the lifespan of data in a network. Each time a packet is forwarded by a router, its TTL value is decremented by one. If the TTL reaches zero, the packet is discarded. This default setting of 64 helps to avoid infinite loops in the network by ensuring that packets will eventually be dropped if they circulate without reaching their destination. This value is often chosen because it provides a balance: it's high enough to allow for deep routing and diverse paths throughout a network, while still being low enough to protect against routing errors that could trap packets in a loop for too long. Other common TTL values, such as 128 and 255, may be used by different operating systems or devices, but for standard Linux distributions, 64 is typically the value assigned. A TTL of 32 is less common and often seen in other contexts or specific configurations.