An IP address is a frequently mentioned technical term that a business owner does not need to understand in detail — but should grasp three practical implications: why some services require a static IP, what IP whitelisting is, and when it matters whether you have IPv4 or IPv6.
For broader IT context, see the pillar IT Basics for Business Owners. For the glossary entry, see /en/glossary/ip-adresa.
What Is an IP Address
An IP address (Internet Protocol address) is a numerical identification of a device on a network. It works like a postal address — every house has a unique address to which post can be delivered. On the internet, every device (computer, phone, server, router) has a unique IP address to which data is delivered.
Example: when you type modulario.com into a browser, the following process occurs:
- The browser asks a DNS server: “What is the IP address for modulario.com?”
- The DNS server replies, for example, “195.46.106.12”
- The browser sends the request to this IP address
- The modulario.com server responds with HTML content
Without IP addresses, the internet would not function — every communication must have a sender and a recipient.
IPv4 vs. IPv6
IPv4
The original standard from 1981. Format: 4 numbers 0-255 separated by dots, e.g. 192.168.1.1 or 8.8.8.8.
Limit: 4.3 billion addresses (2^32). By 2026, practically exhausted. Solution: NAT (Network Address Translation) — multiple devices on a network share one public IP.
IPv6
The new standard from 1998, gradually deployed from 2012. Format: 8 groups of hexadecimal numbers, e.g. 2a01:0abc:0000:0000:0000:0000:0000:0123 (abbreviated 2a01:abc::123).
Address space: 3.4 × 10^38 (practically unlimited).
In 2026, most EU internet providers support IPv6 (dual-stack — IPv4 + IPv6 in parallel). For a business owner, it is sufficient to verify that your ISP offers IPv6.
Public vs. Private IP
Public IP
Routable from the internet. Assigned by the internet service provider (ISP) — typically one per business connection.
You can check your current public IP via whatismyip.com.
Private IP
Not accessible from the internet. Used in the company’s local network (LAN). Standard ranges:
10.0.0.0 – 10.255.255.255(large networks)172.16.0.0 – 172.31.255.255192.168.0.0 – 192.168.255.255(most common in small businesses / homes)
The router assigns private IPs to devices on the network and translates communication via NAT to the public IP.
Static vs. Dynamic IP
Dynamic IP
Changes over time — on router restart, periodically (every few days), or on DHCP lease renewal.
The default for most home and small business connections. Inexpensive, sufficient for ordinary internet browsing.
Static IP
Permanent, unchanging IP address. Reserved for a specific customer.
Cost: 5–20/month from your internet provider. Sometimes included in a business package at no extra charge.
When Your Business Needs a Static IP
A static public IP makes sense in these scenarios:
1. IP Whitelisting in Cloud Applications
Many cloud services allow you to restrict access to specific IP addresses only. Examples:
- Microsoft 365 Conditional Access — sign-in only from the company IP, blocked from elsewhere
- AWS, Azure, Google Cloud — admin consoles accessible only from the company IP
- Banking — some banks allow IP whitelisting for online banking
- ERP / CRM — Modulario allows IP whitelisting for admin actions
Without a static IP, you cannot use these security controls.
2. Your Own Server / E-mail / VPN
If your business hosts:
- E-mail server — DNS MX records must point to a permanent IP
- Web server — A records for your domain point to a permanent IP
- VPN endpoint — remote employees connect to a fixed IP
- Private cloud (Nextcloud, self-hosted Bitwarden) — fixed IP required
3. Professional Image
A static IP signals a serious business. Some B2B partnerships require a static IP during due diligence.
4. Customer Monitoring
Some clients monitor their supplier’s availability via ping to a static IP — for B2B service businesses, this is a common requirement.
CGNAT: The Hidden Trap
In 2026, some ISPs (especially mobile operators) use CGNAT (Carrier-Grade NAT) — multiple customers share one public IP. Consequences:
- VPN may not work or has an unstable connection
- Some applications fail (online gaming, P2P)
- No port forwarding — you cannot host a server
- Geo-location may be incorrect — the IP is shared with people in other cities or regions
Solution: explicitly ask your provider for a static public IP, not just “business internet”.
DNS and Domains
DNS (Domain Name System) translates a domain name into an IP address. Without DNS you would need to remember numerical IP addresses (e.g. 8.8.8.8 instead of google.com).
For a business, DNS records are configurable via your domain registrar. The most important record types:
- A record — domain → IPv4 address
- AAAA record — domain → IPv6 address
- MX record — where e-mail for the domain is delivered
- TXT record — text (often SPF, DKIM, DMARC for e-mail security; or domain verification for Google, Microsoft)
- CNAME record — alias of one domain to another
For a business owner, it is sufficient to know that DNS controls “where your domain points”.
IP and Security: Practical Implications
Audit Log and Forensics
In a security incident, the IP address is a key clue. Modulario’s audit log records:
- The user’s IP address at login
- The IP from which every change was made
- Geo-location of the IP (continent, country)
An attack from a foreign IP where your business has no employees is a signal.
Geo-Blocking
For regulated sectors or high-security environments, you can block access from certain countries — for example, blocking access from known sources of attacks.
IP Reputation
Some IP addresses are on blacklists — due to past attacks, malware, or spam. If your business receives a blacklisted IP (rare, but possible), e-mail may not be delivered and some services will block you.
Solution: when obtaining a static IP, check it via MXToolbox.
What to Ask When Choosing an ISP
Questions to ask a business internet provider:
- What are the upload/download speeds? For 2026, minimum 100/100 Mbit for a mid-sized business, 1 Gbit for larger businesses.
- Is a static public IP included? Ask explicitly.
- IPv6 dual-stack? Yes = good.
- CGNAT or full public IP? Full public IP = good.
- SLA and uptime guarantee? For a business, minimum 99.9%.
- Backup connection? For critical businesses, 4G/5G failover from a different provider.
Frequently Asked Questions
What is the difference between a static and dynamic IP address? A static IP address does not change — the device has it permanently assigned. A dynamic IP changes (typically on every router restart, or periodically). For business use, a static public IP is desirable for: hosting your own server, e-mail server, VPN endpoint, IP whitelisting in ERP, customer monitoring of your service. For ordinary internet browsing from a laptop, a dynamic IP is entirely sufficient.
Should I get a static IP address for my business? For a business, yes — in most cases. Cost: 5–20/month from your internet provider. Benefits: stable DNS records, IP whitelisting in cloud applications (ERP, banking, Microsoft 365 Conditional Access), professional image with clients (a static IP signals a serious business). Without a static IP you are typically behind CGNAT (carrier-grade NAT), which complicates VPN and some applications.
What is IPv6 and do I need to care about it? IPv4 (format 195.168.1.1) has only 4.3 billion addresses — the address space is exhausted. IPv6 (format 2a01:abc::123) is the new standard with a practically unlimited number of addresses. In 2026, most internet providers in the EU support IPv6 dual-stack (both in parallel). For a business owner, it is sufficient to know: your internet provider should offer IPv6, and your business systems should ideally support both versions. The details are handled by IT.