我的系统运行的是 Ubuntu 16.04 LTS，自从我开始使用它以来，我一直面临一个奇怪的问题。很多时候，当我尝试在浏览器（Firefox）上打开一个网站时，系统会提示“未找到服务器”，只有在多次刷新页面后才能进入该网页。这个问题并不总是发生，也不会同时发生在每个网站上，但它确实发生得足够频繁，让我很恼火。
有人可以解释一下这个问题吗？
附言：这个问题似乎是 16.04 独有的。我使用 LAN 连接，其他使用此连接的人都没有这个问题（尽管他们都没有运行 16.04）。另外，我之前在同一系统上使用过 12.04，它运行良好。
编辑
tracepath google.com
1?: [LOCALHOST] pmtu 1500
1: 192.168.0.1 0.647ms
1: 192.168.0.1 0.706ms
2: 10.119.246.117 1.054ms
3: 10.161.18.177 9.200ms asymm 7
4: 10.255.235.197 8.859ms asymm 7
5: 10.119.73.122 9.298ms
6: no reply
7: no reply
8: no reply
9: no reply
10: no reply
11: no reply
12: no reply
13: no reply
14: no reply
15: no reply
16: no reply
17: no reply
等等。
ping -c 20ping -c 20 google.com
PING google.com (216.58.220.206) 56(84) bytes of data.
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=1 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=2 ttl=56 time=45.4 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=3 ttl=56 time=46.1 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=4 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=5 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=6 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=7 ttl=56 time=45.4 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=8 ttl=56 time=45.5 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=9 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=10 ttl=56 time=45.6 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=11 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=12 ttl=56 time=45.6 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=13 ttl=56 time=45.7 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=14 ttl=56 time=45.5 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=15 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=16 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=17 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=18 ttl=56 time=45.3 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=19 ttl=56 time=45.2 ms
64 bytes from del01s08-in-f14.1e100.net (216.58.220.206): icmp_seq=20 ttl=56 time=45.3 ms
--- google.com ping statistics ---
20 packets transmitted, 20 received, 0% packet loss, time 19027ms
rtt min/avg/max/mdev = 45.289/45.459/46.109/0.307 ms
还有这个
cat /etc/nsswitch.conf
# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.
passwd: compat
group: compat
shadow: compat
gshadow: files
hosts: files mdns4_minimal [NOTFOUND=return] dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
和这个
computer
description: Desktop Computer
product: P6-2356IN (H3W39AA#ACJ)
vendor: Hewlett-Packard
serial: [REMOVED]
width: 64 bits
capabilities: smbios-2.7 dmi-2.7 vsyscall32
configuration: boot=normal chassis=desktop family=103C_53316J G=D sku=H3W39AA#ACJ uuid=[REMOVED]
*-core
description: Motherboard
product: 2ABF
vendor: Foxconn
physical id: 0
version: 3.10
*-firmware
description: BIOS
vendor: AMI
physical id: 0
version: 8.12
date: 12/14/2012
size: 64KiB
capacity: 8128KiB
capabilities: pci pnp upgrade shadowing cdboot bootselect edd int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification netboot uefi
*-cache:0
description: L2 cache
physical id: 23
slot: CPU Internal L2
size: 1MiB
capacity: 1MiB
capabilities: internal write-through unified
configuration: level=2
*-cache:1
description: L1 cache
physical id: 24
slot: CPU Internal L1
size: 256KiB
capacity: 256KiB
capabilities: internal write-through data
configuration: level=1
*-cache:2
description: L3 cache
physical id: 25
slot: CPU Internal L3
size: 6MiB
capacity: 6MiB
capabilities: internal write-back unified
configuration: level=3
*-cpu
description: CPU
product: Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz
vendor: Intel Corp.
physical id: 27
bus info: cpu@0
version: Intel(R) Core(TM) i5-3330 CPU @ 3.00GHz
slot: SOCKET 0
size: 1707MHz
capacity: 3800MHz
width: 64 bits
clock: 100MHz
capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm epb tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts cpufreq
configuration: cores=4 enabledcores=4 threads=4
*-memory
description: System Memory
physical id: 28
slot: System board or motherboard
size: 4GiB
*-bank:0
description: DIMM [empty]
product: [Empty]
vendor: [Empty]
physical id: 0
serial: [REMOVED]
slot: DIMM1
*-bank:1
description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
product: RMR5040ED58E9W1600
vendor: Ramaxel
physical id: 1
serial: [REMOVED]
slot: DIMM3
size: 4GiB
width: 64 bits
clock: 1600MHz (0.6ns)
*-pci
description: Host bridge
product: Xeon E3-1200 v2/3rd Gen Core processor DRAM Controller
vendor: Intel Corporation
physical id: 100
bus info: pci@0000:00:00.0
version: 09
width: 32 bits
clock: 33MHz
configuration: driver=ivb_uncore
resources: irq:0
*-pci:0
description: PCI bridge
product: Xeon E3-1200 v2/3rd Gen Core processor PCI Express Root Port
vendor: Intel Corporation
physical id: 1
bus info: pci@0000:00:01.0
version: 09
width: 32 bits
clock: 33MHz
capabilities: pci pm msi pciexpress normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:25 ioport:e000(size=4096) memory:f6000000-f70fffff ioport:e8000000(size=167772160)
*-display
description: VGA compatible controller
product: GF119 [GeForce GT 620 OEM]
vendor: NVIDIA Corporation
physical id: 0
bus info: pci@0000:01:00.0
version: a1
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress vga_controller bus_master cap_list rom
configuration: driver=nouveau latency=0
resources: irq:28 memory:f6000000-f6ffffff memory:e8000000-efffffff memory:f0000000-f1ffffff ioport:e000(size=128) memory:f7000000-f707ffff
*-multimedia
description: Audio device
product: GF119 HDMI Audio Controller
vendor: NVIDIA Corporation
physical id: 0.1
bus info: pci@0000:01:00.1
version: a1
width: 32 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=snd_hda_intel latency=0
resources: irq:17 memory:f7080000-f7083fff
*-communication
description: Communication controller
product: 6 Series/C200 Series Chipset Family MEI Controller #1
vendor: Intel Corporation
physical id: 16
bus info: pci@0000:00:16.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list
configuration: driver=mei_me latency=0
resources: irq:29 memory:f730a000-f730a00f
*-usb:0
description: USB controller
product: 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2
vendor: Intel Corporation
physical id: 1a
bus info: pci@0000:00:1a.0
version: 05
width: 32 bits
clock: 33MHz
capabilities: pm debug ehci bus_master cap_list
configuration: driver=ehci-pci latency=0
resources: irq:16 memory:f7308000-f73083ff
*-usbhost
product: EHCI Host Controller
vendor: Linux 4.4.0-47-generic ehci_hcd
physical id: 1
bus info: usb@1
logical name: usb1
version: 4.04
capabilities: usb-2.00
configuration: driver=hub slots=2 speed=480Mbit/s
*-usb
description: USB hub
product: Integrated Rate Matching Hub
vendor: Intel Corp.
physical id: 1
bus info: usb@1:1
version: 0.00
capabilities: usb-2.00
configuration: driver=hub slots=4 speed=480Mbit/s
*-usb
description: Keyboard
product: USB Receiver
vendor: Logitech
physical id: 1
bus info: usb@1:1.1
version: 29.00
capabilities: usb-2.00
configuration: driver=usbhid maxpower=98mA speed=12Mbit/s
*-multimedia
description: Audio device
product: 6 Series/C200 Series Chipset Family High Definition Audio Controller
vendor: Intel Corporation
physical id: 1b
bus info: pci@0000:00:1b.0
version: 05
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=snd_hda_intel latency=0
resources: irq:30 memory:f7300000-f7303fff
*-pci:1
description: PCI bridge
product: 6 Series/C200 Series Chipset Family PCI Express Root Port 1
vendor: Intel Corporation
physical id: 1c
bus info: pci@0000:00:1c.0
version: b5
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:16
*-pci:2
description: PCI bridge
product: 6 Series/C200 Series Chipset Family PCI Express Root Port 2
vendor: Intel Corporation
physical id: 1c.1
bus info: pci@0000:00:1c.1
version: b5
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:17 memory:f7200000-f72fffff
*-network DISABLED
description: Wireless interface
product: RT5390R 802.11bgn PCIe Wireless Network Adapter
vendor: Ralink corp.
physical id: 0
bus info: pci@0000:03:00.0
logical name: wlp3s0
version: 00
serial: [REMOVED]
width: 32 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=rt2800pci driverversion=4.4.0-47-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
resources: irq:17 memory:f7200000-f720ffff
*-pci:3
description: PCI bridge
product: 6 Series/C200 Series Chipset Family PCI Express Root Port 6
vendor: Intel Corporation
physical id: 1c.5
bus info: pci@0000:00:1c.5
version: b5
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:17 ioport:d000(size=4096) memory:f7100000-f71fffff
*-network
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:04:00.0
logical name: enp4s0
version: 06
serial: [REMOVED]
size: 100Mbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168e-2.fw ip=[REMOVED] latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
resources: irq:26 ioport:d000(size=256) memory:f7104000-f7104fff memory:f7100000-f7103fff
*-usb:1
description: USB controller
product: 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1
vendor: Intel Corporation
physical id: 1d
bus info: pci@0000:00:1d.0
version: 05
width: 32 bits
clock: 33MHz
capabilities: pm debug ehci bus_master cap_list
configuration: driver=ehci-pci latency=0
resources: irq:23 memory:f7307000-f73073ff
*-usbhost
product: EHCI Host Controller
vendor: Linux 4.4.0-47-generic ehci_hcd
physical id: 1
bus info: usb@2
logical name: usb2
version: 4.04
capabilities: usb-2.00
configuration: driver=hub slots=2 speed=480Mbit/s
*-usb
description: USB hub
product: Integrated Rate Matching Hub
vendor: Intel Corp.
physical id: 1
bus info: usb@2:1
version: 0.00
capabilities: usb-2.00
configuration: driver=hub slots=6 speed=480Mbit/s
*-usb:0
description: Generic USB device
product: SLP
vendor: SAMSUNG
physical id: 4
bus info: usb@2:1.4
version: 4.00
serial: [REMOVED]
capabilities: usb-2.00
configuration: driver=usbfs maxpower=48mA speed=480Mbit/s
*-usb:1
description: Mass storage device
product: Mass Storage Device
vendor: Generic
physical id: 6
bus info: usb@2:1.6
logical name: scsi5
version: 1.00
serial: [REMOVED]
capabilities: usb-2.00 scsi emulated scsi-host
configuration: driver=usb-storage maxpower=100mA speed=480Mbit/s
*-disk
description: SCSI Disk
physical id: 0.0.0
bus info: scsi@5:0.0.0
logical name: /dev/sdb
configuration: logicalsectorsize=512 sectorsize=512
*-isa
description: ISA bridge
product: H61 Express Chipset Family LPC Controller
vendor: Intel Corporation
physical id: 1f
bus info: pci@0000:00:1f.0
version: 05
width: 32 bits
clock: 33MHz
capabilities: isa bus_master cap_list
configuration: driver=lpc_ich latency=0
resources: irq:0
*-storage
description: SATA controller
product: 6 Series/C200 Series Chipset Family SATA AHCI Controller
vendor: Intel Corporation
physical id: 1f.2
bus info: pci@0000:00:1f.2
version: 05
width: 32 bits
clock: 66MHz
capabilities: storage msi pm ahci_1.0 bus_master cap_list
configuration: driver=ahci latency=0
resources: irq:27 ioport:f070(size=8) ioport:f060(size=4) ioport:f050(size=8) ioport:f040(size=4) ioport:f020(size=32) memory:f7306000-f73067ff
*-serial UNCLAIMED
description: SMBus
product: 6 Series/C200 Series Chipset Family SMBus Controller
vendor: Intel Corporation
physical id: 1f.3
bus info: pci@0000:00:1f.3
version: 05
width: 64 bits
clock: 33MHz
configuration: latency=0
resources: memory:f7305000-f73050ff ioport:f000(size=32)
*-scsi:0
physical id: 1
logical name: scsi1
capabilities: emulated
*-disk
description: ATA Disk
product: ST3500414CS
vendor: Seagate
physical id: 0.0.0
bus info: scsi@1:0.0.0
logical name: /dev/sda
version: CA14
serial: [REMOVED]
size: 465GiB (500GB)
capabilities: gpt-1.00 partitioned partitioned:gpt
configuration: ansiversion=5 guid=f83e4e9e-ebeb-4ea7-b272-14a761ba61bd logicalsectorsize=512 sectorsize=512
*-volume:0 UNCLAIMED
description: Windows FAT volume
vendor: mkfs.fat
physical id: 1
bus info: scsi@1:0.0.0,1
version: FAT32
serial: [REMOVED]
size: 510MiB
capacity: 511MiB
capabilities: boot fat initialized
configuration: FATs=2 filesystem=fat name=EFI System Partition
*-volume:1
description: EXT4 volume
vendor: Linux
physical id: 2
bus info: scsi@1:0.0.0,2
logical name: /dev/sda2
logical name: /
version: 1.0
serial: [REMOVED]
size: 461GiB
capabilities: journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized
configuration: created=2016-09-08 18:49:43 filesystem=ext4 lastmountpoint=/ modified=2016-11-19 08:19:23 mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,data=ordered mounted=2016-11-19 08:19:29 state=mounted
*-volume:2
description: Linux swap volume
vendor: Linux
physical id: 3
bus info: scsi@1:0.0.0,3
logical name: /dev/sda3
version: 1
serial: [REMOVED]
size: 4052MiB
capacity: 4052MiB
capabilities: nofs swap initialized
configuration: filesystem=swap pagesize=4095
*-scsi:1
physical id: 2
logical name: scsi4
capabilities: emulated
*-cdrom
description: DVD-RAM writer
product: DVD A DH16ACSHR
vendor: hp
physical id: 0.0.0
bus info: scsi@4:0.0.0
logical name: /dev/cdrom
logical name: /dev/cdrw
logical name: /dev/dvd
logical name: /dev/dvdrw
logical name: /dev/sr0
version: JHG6
capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
configuration: ansiversion=5 status=nodisc
*-power UNCLAIMED
product: Standard Efficiency
physical id: 1
capacity: 32768mWh
答案1
首先检查您的网络管理器。您的 IPv6 是否启用并不会引起太多关注，但是当您的 IPv4 处于静态时，您就会遇到问题。确保您的 IPv4 处于动态 IP 地址的获取模式。然后就像 Windows 一样禁用并启用它几秒钟，刷新。然后再次打开您的浏览器。
答案2
您可能遇到了 DNS 问题，主要是由于本地 DNS 服务器速度慢所致。您可以通过调用以下命令来查找当前的 DNS 设置：
nmcli dev show | grep DNS
尝试将您的 DNS 设置为类似的东西4.2.2.4。
为了更好地诊断，请执行此处列出的步骤：
未找到服务器 - 解决连接问题
https://support.mozilla.org/en-US/kb/server-not-found-connection-problem
你应该测试其他浏览器，根据结果，你就能准确地找出问题的根源。但根据你的说法，最有可能的是 DNS 问题。这可以通过 DNS 预取来解决，尽管它有一些缺点。