An IT technician is troubleshooting name resolution issues on an administrator workstation. The technician issues an `nslookup` command for `app.finance.local` and receives a successful reply pointing to `192.168.10.50`. However, when attempting to ping `app.finance.local` from the same machine, the system attempts to send traffic to `10.0.0.99` and times out.
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C:\Users\Admin> nslookup app.finance.local
Server: dns01.corp.internal
Address: 10.0.0.1
Name: app.finance.local
Address: 192.168.10.50
C:\Users\Admin> ping app.finance.local
Pinging app.finance.local [10.0.0.99] with 32 bytes of data:
Request timed out.
Which of the following is the most likely cause of the discrepancy in resolved IP addresses?
- A static entry for app.finance.local mapping to 10.0.0.99 is present in the local hosts file.Cevap
- BThe DNS server dns01.corp.internal has a misconfigured CNAME record instead of an A record.
- CThe client workstation is configured to use TCP port 53 for ping requests and UDP port 53 for nslookup queries.
- DThe nslookup utility received an unauthoritative non-recursive response due to a misconfigured root hint.
Cevap
A static entry for app.finance.local mapping to 10.0.0.99 is present in the local hosts file.
The correct answer identifies that a static entry exists in the local hosts file. Standard operating system commands like `ping` utilize the OS name resolution pipeline, which evaluates the local `hosts` file and resolver cache before sending requests to remote DNS servers. The diagnostic tool `nslookup`, however, bypasses local system files and queries the DNS server directly. The discrepancy between `nslookup` (192.168.10.50) and `ping` (10.0.0.99) indicates that a local `hosts` file entry is overriding the DNS server's record for normal application traffic.
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Anahtar Kavram
Operating System Hostname Resolution Order vs. Direct DNS Diagnostics (nslookup vs. OS Resolver)