A network technician is investigating a connectivity issue on a Linux workstation. When executing `nslookup repo.corp.local`, the command returns an IP address of `10.50.10.25` from the internal DNS server. However, ping commands and web browser traffic directed to `repo.corp.local` consistently attempt to connect to `10.50.10.99`, resulting in connection timeouts.
Which of the following is the most likely cause of this name resolution discrepancy?
- The local /etc/hosts file contains an outdated entry mapping repo.corp.local to 10.50.10.99.Cevap
- BThe nslookup utility misinterpreted a cached response from the default gateway instead of querying the authoritative DNS server.
- CThe DNS server is missing an AAAA record for the host, forcing the operating system to fall back to an obsolete PTR record.
- DThe network firewall is blocking TCP port 53 traffic while allowing UDP port 53 traffic.
Cevap
The local /etc/hosts file contains an outdated entry mapping repo.corp.local to 10.50.10.99.
The correct answer identifies that the local `/etc/hosts` file contains an outdated mapping. In operating systems like Linux and Windows, standard applications (such as web browsers or the `ping` utility) follow the system's name resolution order, which prioritizes the local `hosts` file before sending a query to a DNS server. In contrast, diagnostic tools like `nslookup` bypass the local `hosts` file and query the configured DNS server directly. Therefore, `nslookup` retrieves the correct IP address (`10.50.10.25`) from DNS, while applications read the stale entry (`10.50.10.99`) from `/etc/hosts`.
Adım Adım Çözüm
Anahtar Kavram
Operating System Name Resolution Order vs Direct DNS Diagnostic Utility Behavior