Cisco Certified Network Associate (CCNA) Practice Exam

When configuring NAT, what does overload allow for?

1. Multiple internal IPs to use a single external IP

2. Direct access to external networks

3. Static IP assignments only

4. Enhanced routing performance

The correct answer is: Multiple internal IPs to use a single external IP

Overload is a feature in NAT (Network Address Translation) that allows multiple internal IP addresses to be mapped to a single external IP address. This is particularly useful in conserving the limited number of available public IP addresses. By using overload, the NAT router can track multiple sessions from various internal hosts and can maintain a single external IP address by utilizing different port numbers for each connection. This allows for efficient use of IP addresses while enabling multiple devices on a private network to access external networks, such as the internet, simultaneously. This functionality is critical in environments where there is a shortage of public IP addresses and is commonly referred to as PAT (Port Address Translation). It enhances the ability of networks to communicate with external services without requiring a unique public IP address for each internal device. This capability is especially useful in home networks and small businesses where multiple devices need internet access but only a single IP from an Internet Service Provider is available.