MDNS 多播 DNS 和 resolv.conf 文件

MDNS（多播 dns）問題會導致 resolv.conf 文件中出現重複的行嗎？

例如，我們有以下 resolv.conf 文件

more /etc/resolv.conf
search coronplesdf.hh.com
server 108.16.1.71
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com
domain coronplesdf.hh.com

例如我們從 dmesg 得到什麼

[6484420.812643] raid6: using avx2x2 recovery algorithm
[6484420.859086] Btrfs loaded
[6484426.278636] nr_pdflush_threads exported in /proc is scheduled for removal
[6484708.776239] ixgbe 0000:04:00.0: invalid short VPD tag 06 at offset 4
[6900952.098901] perf: interrupt took too long (6247 > 6167), lowering kernel.perf_event_max_sample_rate to 32000
[7372848.819396] Peer 0000:0000:0000:0000:0000:ffff:0a15:f030:1054/8042 unexpectedly shrunk window 3002395993:3002395997 (repaired)
[8139485.039423] Turbo disabled by BIOS or unavailable on processor
[8380300.891343] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380320.890541] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380440.896206] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380460.895001] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380463.207397] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380467.316531] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380468.363352] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380469.332044] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380489.330943] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380509.329849] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380529.328678] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380549.468256] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380569.326474] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380589.340946] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380609.339969] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380619.870472] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380620.964216] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380621.979847] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380641.869255] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380661.883737] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69

第 2 層網路性能優化/怪癖不應該影響resolv.conf. 我敢打賭，您的某些 devops 腳本上的一些非冪等操作是在多個呼叫中添加/添加域行。

此外，mDNS 不使用中心點，並且獨立於正常 DNS；說話的設備向整個網路宣布它們的名稱/IP 地址（m 代表多播）。由於我在 DNS 中擁有一切，我通常會在“我的”企業伺服器中停止 mDNS 守護程序/avahi。

不，錯誤的 MDNS 數據包校驗和不應導致多domain行輸入，/etc/resolv.conf反之亦然。

訊息

UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69

將表明 IP 為 82.2.33.1 的系統正在接收來自 73.2.33.11 的錯誤 UDP 數據包，因此 IP 為 73.2.33.11 的系統可能存在軟體錯誤或某些 NIC 硬體故障。它也可能是通過故意發送壞包並查看您的系統如何/是否會響應它們來嘗試探測您的系統。

我假設您出於隱私考慮修改了 IP 地址，因為在同一個網段中擁有像 73.xxx 和 82.xxx 這樣的 IP 通常沒有意義。MDNS 通常僅在單個網段內有用，因此如果 73.2.33.11 不是您的本地網路的一部分，您可能希望在路由器（或專用防火牆設備，如果你有一個）。

引用自：https://unix.stackexchange.com/questions/584332