IP address
An IP address is the number that identifies a device or internet connection on a network, so that traffic can be delivered to the right place. The question set does not ask you to list IP addresses, but an IP allow list can protect a firewall admin interface (A4.11), and Cyber Essentials Plus scans every public address you use.
- Term
- IP address
- Also known as
- Internet Protocol address, Public IP address, IPv4, IPv6
- Category
- Networks and firewalls
- Requirement area
- 1. Firewalls
- Reviewed against
- Requirements v3.3
What does the term IP address mean in Cyber Essentials?
An IP address is the number that identifies a device or internet connection on a network, so that traffic can be delivered to the right place.
How does IP address apply to Cyber Essentials?
In plain terms
An IP address works like a postal address for network traffic. Devices inside your office have private addresses that only mean something on your own network. Your internet connection has a public address, given to you by your internet service provider, which is what the rest of the internet sees. An address looks like 81.2.69.160 in the older format (IPv4) or a longer string of letters and numbers in the newer one (IPv6).
What Cyber Essentials asks
For the self-assessment you do not hand over addresses. A2.4 says "Do not provide IP addresses or other technical information", and A2.5 says "You are not required to list any IP addresses, MAC addresses or serial numbers."
Addresses matter in two other places. If your firewall's settings can be reached over the internet, the requirements accept "an IP allow list that limits access to a small range of trusted addresses combined with a properly managed password authentication approach" as one of two protections (A4.9 to A4.11). And for Cyber Essentials Plus, test case 1 starts with the assessor told to "Identify all of the IP addresses currently in use by the Applicant. This must include IaaS where used", then scan them all.
Common mistakes
- Forgetting a public address at a second site or on a cloud server, which then gets missed before the external scan.
- An allow list that includes whole ranges rather than "a small range of trusted addresses".
See Test 1: the external vulnerability scan and A4.11. Related: static IP address, allow listing, DNS.
Related terms
- Internet service provider (ISP)An internet service provider, or ISP, is the company that supplies your internet connection and often the router that comes with it.
- Static IP addressA static IP address is a public internet address that stays the same over time, unlike a dynamic address that your broadband provider can change without notice.
- Allow listing (application allow listing)Allow listing is a malware protection option in which only approved applications, restricted by code signing, are allowed to execute on devices.
- DNS (Domain Name System)DNS, the Domain Name System, is the internet's address book that turns names people can read, such as example.co.uk, into the number addresses computers use.
- NAT (network address translation)NAT, network address translation, is the way a router lets many devices on your network share one public internet address by swapping addresses as traffic passes through.
- Network segregationNetwork segregation is splitting a network into separate parts, so that devices in one part cannot freely reach devices in another.
Frequently asked questions
An IP address is the number that identifies a device or internet connection on a network, so that traffic can be delivered to the right place.
In the 2026 Danzell question set, IP address comes up at A2.4, A2.5, A4.11. Read those questions against the definition above so your answers use the term the way the assessor will.
IP address relates to 1. Firewalls in the NCSC's Cyber Essentials: Requirements for IT Infrastructure v3.3. Read that section for the control your answers must show.
Would you pass the 2026 question set?
Answer 24 yes or no questions, built by the assessors who mark Cyber Essentials, and get a readiness score in about five minutes, with any auto-fail questions you miss flagged first in your results.