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Most home internet connections do not permanently assign one public IP address. Instead, they use dynamic IP addressing, where the ISP temporarily assigns an address from its available IP pool for as long as it is needed.

IP addresses are usually assigned through DHCP (Dynamic Host Configuration Protocol). A new IP address may be assigned when the lease period expires, or when a router, optical modem, or other internet equipment is powered off and on again. In typical home internet environments, occasional public IP changes are normal.

When using mobile data, the IP address may change even more often. The externally visible IP can change when a smartphone moves to another base station, when mapping information changes in the carrier's CGN (Carrier-Grade NAT) system, or when the device reconnects to the network.

Using a VPN can also make your IP address appear to change. In that case, the IP shown to external sites is not your actual internet line IP, but the VPN server's IP. If the VPN disconnects or reconnects to another country or server, the queried IP address can change as well.

If you need an IP address that does not change for business service, server operation, remote access, or firewall policies, you should request a static public IP service from your ISP. If you want to maintain external access in a dynamic IP environment without that cost, DDNS (Dynamic DNS) can be useful because it keeps a fixed domain name connected even when the IP changes. This is helpful for accessing firewall or router management pages, NAS devices, CCTV, and similar internal devices from outside.

In short, it is natural for IP addresses to change from time to time on normal home internet or mobile networks. If your environment requires the address to remain the same, use a static IP service or configure DDNS when appropriate.

A public IP address is naturally sent to remote servers during internet communication such as visiting websites, sending email, or using apps. In general, an IP address alone does not reveal an exact home address, name, identity information, or precise GPS location.

However, an IP address can be used to estimate rough country or region, ISP or hosting provider, VPN or proxy usage, and whether the connection belongs to a company or institution network. If a router, NAS, CCTV, SSH, RDP, web service, or other system is exposed from that IP and configured weakly, it may become a target for port scanning, brute-force login attempts, vulnerability exploitation, or DDoS attacks.

Individual users can reduce risk by changing the router admin password, updating firmware, removing unnecessary port forwarding, disabling remote management, and using a firewall. If you want to hide your location or access information, you can use a trusted VPN or proxy.

Server operators should allow only necessary ports and restrict management ports by source IP. Using CDN, reverse proxy, WAF, or DDoS protection services can also reduce origin server IP exposure and attack risk.

In summary, exposing an IP address does not automatically mean personal information has leaked. But if services are exposed externally, security settings should be reviewed carefully.

This happens because of NAT (Network Address Translation).

Companies, schools, and cafes usually receive one or a small number of public IP addresses from an ISP, while assigning different private IP addresses such as 192.168.x.x to internal users.

When users access the external internet, a router or gateway translates their internal private IPs into the representative public IP. Because of this, external websites and servers see multiple users inside the same network as connecting from the same public IP. This is often called a shared IP.

This structure can lead to the following situations.

• If one user performs abnormal activity such as spam sending or attack attempts and the public IP is listed on a threat list, other users on the same network may also be affected by blocking or restrictions from external services.
• Because multiple users share one public IP, advertising and tracking accuracy can be reduced, and some sites may judge the traffic as abnormal and require extra verification such as reCAPTCHA.
• Some games or services may detect multiple connections from the same IP and apply connection limits or usage restrictions.

This is normal behavior in NAT environments.

However, the public IP seen from outside is not enough to identify which internal user made a connection. Accurate identification requires additional information such as connection time, port information, internal DHCP logs, and authentication logs. For easier user tracking and management, some companies and institutions assign fixed private IPs per user instead of relying only on DHCP.

A public IP is an address that is routed across the global internet. It is used for website access, server operation, and communication with external networks, and it is managed so that it does not overlap globally.

A private IP is an address used only inside internal networks such as homes, companies, and schools. Common private IP ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. The same private IP can be used at the same time in countless home and company networks around the world. For example, 192.168.0.1 may be used as the default gateway address on many home routers.

When a device using a private IP accesses the internet, a router or firewall translates the private IP into a public IP through NAT (Network Address Translation). Therefore, the address seen by external websites or servers is not the user's private IP, but the public IP representing that network.

For this reason, private IPs are not directly looked up or accessed from the external internet. Private IPs are meaningful only inside the internal network, and from outside only the public IP translated through NAT can be seen.

Unlike what is often shown in movies or dramas, finding a home address from IP tracking alone is not realistic. An IP address alone usually cannot identify an individual's exact location, and confirming precise user information may require cooperation from the ISP or procedures through the relevant authorities.

Location information from an IP address is generally based on GeoIP databases. These databases often map an IP range to the location registered or operated by the ISP, such as a headquarters, data center, or network operations center (NOC). As a result, the displayed location may differ from the actual user location.

Approximate accuracy is usually as follows.

• Country level: Relatively accurate
• State or province level: Somewhat useful as a reference
• City level: Varies greatly depending on environment, often more accurate in large cities and less accurate in rural areas
• Exact latitude/longitude or street address: Almost impossible to infer reliably

Accuracy can be even lower in special environments.

• Mobile IP: The carrier backbone or gateway location may be shown, and it can differ from the real location by tens of kilometers or more
• VPN or proxy: The VPN or proxy server location is shown and is unrelated to the actual user location
• Satellite internet: The ground gateway location may be shown
• Data center or cloud hosting IP: The data center location is shown and is unrelated to the actual user location

Therefore, IP location information should be treated only as a reference. A normal user cannot identify someone's exact location or identity from an IP address alone.

ASN (Autonomous System Number) is a unique number that identifies an independent network operator on the internet. ISPs, cloud companies, large organizations, and CDN providers can own ASNs, and the ASN shows which organization's network manages or routes the IP.

Anycast is a networking method where multiple servers around the world share one IP address. When a user connects, the traffic is automatically routed to the geographically closest or best-performing server. It is commonly used by DNS and CDN services, and server information may vary depending on the connection location, so it should be considered when interpreting location results.

Bogon means an address that should not normally be used or routed on the public internet. Private IP ranges and unallocated IP ranges are examples. If such an address appears in public internet traffic, it may indicate a network misconfiguration or abnormal traffic.

First, identify why the IP was included in the threat list. Common causes include malware infection on your PC or another device on the same network, abnormal traffic, spam sending, or exposed vulnerable services. If you use a dynamic IP, the address may still be listed because of malicious activity by a previous user.

For home internet users, the IP may have been listed because of activity from someone who previously used the same dynamic IP. In that case, you can reboot the router to receive a new IP, or contact your ISP to ask about IP change or reputation issues.

In a company or server operation environment, first check for internal infection, open proxies, vulnerable mail servers, compromised accounts, abnormal sending logs, and vulnerable services exposed to the internet. If you request removal without fixing the root cause, the IP may be listed again.

Main Remediation Steps

• 1) Check for malware infection: Use antivirus or malware scanners to check PCs and servers and remove infections. Keep the operating system and major programs up to date, and keep router firmware on the latest version where possible.
• 2) Check routers and network equipment: Change the router administrator password to a strong one, and disable external remote management if it is not needed. If possible, prevent the management page from being accessible from all IPs and allow access only from approved IPs.
• 3) Check mail servers and spam sending: If you operate a mail server, review logs for abnormal bulk sending. Compromised accounts, open relay, or weak SMTP configuration can lead to spam listing, so mail authentication settings and sending logs should be checked together.
• 4) Check externally exposed services: Check whether SSH, RDP, FTP, web admin pages, NAS, CCTV, or proxy servers are unnecessarily exposed to the internet. Block unused ports, and apply source IP restrictions, strong passwords, and multi-factor authentication to required services.
• 5) Request blacklist removal: After fixing the cause, you can request removal through the threat intelligence provider's delist, removal, or false positive report process. When submitting the request, explain that infections were removed, vulnerabilities fixed, spam sending stopped, or other issues resolved.

If you repeatedly request removal without resolving the underlying cause, the IP is likely to be listed again quickly. Complete the remediation first, then follow the relevant blacklist provider's delist or removal procedure.

When email is blocked, first check the error message in the bounce email. The bounce message usually includes the receiving server that blocked the email, the reason for blocking, the referenced spam list, related URLs, or an error code. For example, a message such as 550 5.7.1 Service unavailable; client host blocked may appear.

Next, use MyIPInfo to look up the public IP of the sending server and check whether it is listed in threat information or spam lists. In particular, you can quickly check whether it appears on major spam blocking lists such as Spamhaus.

If you operate your own mail server, you should check not only IP reputation but also SPF, DKIM, DMARC, PTR (rDNS), HELO/EHLO name, open relay status, bulk sending logs, and account compromise. If these settings are incorrect or an account is compromised, even legitimate mail may be classified as spam or blocked.

Dynamic IP ranges from home or ordinary internet lines can be disadvantageous for mail sending or blocked under ISP policy or recipient server security policy. If reliable mail delivery is required, using a managed email sending service or fixed-IP mail infrastructure with maintained reputation is usually the most stable and recommended approach.