When is dynamic routing used?

Dynamic routing is used when the network is large, changeable, and requires automatic adaptation of data transmission paths.

Put simply: it is chosen where maintaining routes manually is already inconvenient or unsafe.

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#Main cases when dynamic routing is used

#1. Large networks

When there are:

• many routers
• tens or hundreds of subnets

Manually configuring static routes:

• takes a lot of time
• easily leads to mistakes

Dynamic routing:

• distributes network information on its own
• automatically builds routing tables

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#2. Frequent topology changes

Used when:

• links can go down
• equipment can be disconnected
• networks are often added or removed

In this case:

• routers rebuild routes themselves
• traffic takes an alternative path

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#3. Fault tolerance is required

Dynamic routing is needed when:

• backup links exist
• continuous network availability matters

On failure:

• the primary path is excluded
• a backup is chosen automatically

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#4. Corporate and provider networks

Typical use:

• corporate WANs
• data centers
• provider networks
• the Internet

Without dynamic routing:

• such networks simply could not work normally

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#5. Minimizing manual administration

Used when:

• manual configuration needs to be reduced
• centralized route logic matters
• the network should "maintain itself"

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#When dynamic routing is NOT needed

Important for an interview

It is not worthwhile when:

• the network is small
• the topology is stable
• there are no backup links
• maximum simplicity matters

In such cases, static routing is more often chosen.

In short, for an interview

Dynamic routing is used in large and changeable networks that require automatic building and updating of routes, fault tolerance, and minimal manual configuration.