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A URL does not get looked up as one complete string. DNS normally resolves its host name—such as www.example.com—to one or more IP addresses. A records provide IPv4 addresses; AAAA records provide IPv6 addresses. The result can vary with the DNS resolver, cached data, and time.
What “URL to IP address” means
A URL identifies a resource and indicates how to locate it. Consider https://www.example.com:8443/products?id=3#details:
- Scheme:
https - Host:
www.example.com - Port:
8443 - Path:
/products - Query:
id=3 - Fragment:
details
DNS lookup normally concerns the host name, not the scheme, port, path, query, or fragment. The URL syntax standard, RFC 3986, also allows a URL to contain an IP address directly as its host. In that case, the address is already present and a DNS name lookup is not needed to discover it.
How DNS finds an address
- The application extracts the host name from the URL.
- The device asks its configured DNS resolver for records for that name. In a common setup, this is a recursive resolver.
- If the resolver has a usable cached answer, it may return it. Otherwise, it queries DNS, following referrals as needed to find the relevant authoritative data.
- The DNS response may include A records for IPv4, AAAA records for IPv6, or both.
- The application can use an address to attempt a network connection. Getting an answer does not establish that the website will successfully load.
Google Cloud’s general DNS overview explains the roles of recursive resolvers and authoritative servers and illustrates how a query can follow referrals from the root zone through a top-level domain to a domain’s authoritative name servers.
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What A and AAAA records contain
| Record type | Address family | What the record contains |
|---|---|---|
| A | IPv4 | A 32-bit Internet address, as defined in RFC 1035. |
| AAAA | IPv6 | A single 128-bit IPv6 address, as defined in RFC 3596. |
A host can have multiple address records and can have both A and AAAA records. So asking for “the IP address” can oversimplify the result: a query may return several addresses, and a client may choose among them. Cloudflare’s DNS record documentation describes A and AAAA records as mapping a name to one or multiple addresses and explains that a record’s TTL indicates how long resolvers should cache a response before revalidating it.
Why lookup results can differ
A DNS answer is what a particular resolver returns at a particular time; it is not proof that a name has one permanent address. Records can change, a name can have multiple addresses, and cached answers may remain in use according to their TTL. Resolver location and network configuration can also affect what a user sees.
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When comparing results, note the record type, the number of addresses returned, the resolver queried, when the lookup occurred, and any relevant TTL or cache state. Different answers do not by themselves show that either result is wrong.
How to check a host name
First identify the host in the URL, then query that name. For example, if the URL is https://www.example.com/products, query www.example.com, not the entire URL.
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- PORT FLASHING:The indicator light on the connection port in the NF-8508 device flashes to help accurately locate the cable. Displays port information, including operating speed, duplex mode, and negotiation settings. Port lights flash on the same screen to show the port's operating speed, making it easy to pinpoint lines and ports.
- PoE Testing and Cable Length Test: PoE testing can check cable mapping polarity and voltage of PoE network switches, withstand 60VDC. Automatically detects and switches between 10M/100M/1000M modes, Includes cable tracking, short circuit test, interruption of circuit test and etc The RJ45 cable tester can quickly measure the length of the cable with a range of 200m. Not only network cables, but also phone lines and BNC cables.
dig example.com Aasks for A records.dig example.com AAAAasks for AAAA records.dig +trace google.comtraces resolution through DNS referrals; Google Cloud documents it as an example.
These examples use dig, which may not be installed or available by default on every operating system. The DNS overview from Google Cloud describes the trace example.
Quick Recap
Best Value
- Multi-Function Network Cable Tester: Supports RJ45 (CAT5, CAT5e, CAT6, CAT6A, CAT7) and RJ11 telephone cables. Quickly detects continuity, short circuits, open wires, miswiring, and cable shielding status, ensuring your LAN or phone lines are correctly wired and ready to use.
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- Compact, Lightweight & Durable: Ergonomically designed with sturdy ABS housing, this pocket-sized tester is ideal for on-the-go network engineers, DIYers, and electricians. It’s your go-to toolkit for cable maintenance, upgrades, or new installations.
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Rank #4
- Automatically runs all tests and checks for continuity, open, shorted and crossed wire pairs. Visible LED status display.
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- Connectors: Ethernet Cat 5, Ethernet Cat 5e, Ethernet Cat 6, Ethernet Cat 7, RJ11 6P and RJ45 8P
- Power Source: DC9V Battery Required (not included)
What a DNS result does—and does not—tell you
- No A answer but an AAAA answer, or vice versa: the host may be configured for only one address family.
- Different answers at different times: check which resolver was used and consider TTL and cache state.
- The name resolves, but the site fails to load: DNS has supplied address information, but that alone does not establish that the server, network route, port, TLS connection, or application is working.
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