Your company implements a firewall to protect the internal network, 192.168.1.0/24. Which of the following is incorrect? (Wentz QOTD)
A. 192.168.1.254/24 can be the default gateway.
B. A DHCP client sends the DHCP DISCOVER message with source IP address, 0.0.0.0.
C. The firewall should enable Network Address Translation (NAT) to connect internal hosts to the Internet.
D. The internal network, 192.168.1.0/24 cannot be further subnetted.
Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.
My suggested answer is D. The internal network, 192.168.1.0/24 cannot be further subnetted.
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| IP Address: | 192.168.1.0 |
| Network Address: | 192.168.1.0 |
| Usable Host IP Range: | 192.168.1.1 – 192.168.1.254 |
| Broadcast Address: | 192.168.1.255 |
| Total Number of Hosts: | 256 |
| Number of Usable Hosts: | 254 |
| Subnet Mask: | 255.255.255.0 |
| Wildcard Mask: | 0.0.0.255 |
| Binary Subnet Mask: | 11111111.11111111.11111111.00000000 |
| IP Class: | C |
| CIDR Notation: | /24 |
| IP Type: | Private |
| Short: | 192.168.1.0 /24 |
| Binary ID: | 11000000101010000000000100000000 |
| Integer ID: | 3232235776 |
| Hex ID: | 0xc0a80100 |
| in-addr.arpa: | 0.1.168.192.in-addr.arpa |
| IPv4 Mapped Address: | ::ffff:c0a8.0100 |
| 6to4 Prefix: | 2002:c0a8.0100::/48 |
The internal network, 192.168.1.0/24 can be further subnetted. For example:
- 192.168.1.0/25 (192.168.1.0~192.168.1.127)
- 192.168.1.128/25 (192.168.1.128~192.168.1.255)
In the internal network, 192.168.1.0/24, there are 256 IP addresses available in theory. However, only 254 IP addresses can be configured on hosts per the IPv4 addressing rules, which reserve the first IP address (192.168.1.0) for the network itself and the last one (192.168.1.255) as the broadcast address.
- The IP address of the default gateway can be any IP address from 192.168.1.1 to 192.168.1.254.
- DHCP clients can lease IP addresses from the DHCP server. A DHCP client broadcasts to discover DHCP servers and requests IP addresses because its IP address hasn’t been configured yet.
- As 192.168.1.0/24 belongs to private IP ranges defined in RFC 1918, hosts using private IP addresses cannot connect to the Internet directly. Network Address Translation (NAT) can translate a private IP address to a public IP address and vice versa.
Reference
- Dynamic Host Configuration Protocol
- DHCP (Dynamic Host Configuration Protocol) Basics
- IP Subnet Calculator
- Network Address Translation
貴公司實施了防火牆來保護內部網絡 192.168.1.0/24。 以下哪項不正確？ (Wentz QOTD)
A. 192.168.1.254/24 可以是預設的閘道器。
B. DHCP 客戶端發送來源 IP 地址為 0.0.0.0 的 DHCP DISCOVER 消息。
C. 防火牆應啟用網絡地址轉換 (NAT) 以將內部主機連接到 Internet。
D. 內部網絡 192.168.1.0/24 不能進一步劃分子網路。