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Questions tagged [ttl]

Time To Live is a mechanism to prevent messages from traversing the network indefinitely

Every IP packet has a Time To Live, it is a counter that gets deducted when it passes a router. It prevents a packet from traversing the network endlessly. If the packets TTL reaches 0 it gets discarded. TTL can be a timestamp or a counter.

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Why does TTL sometimes re-increment between DNS queries?

I dig xkcd.com, and I get something like this back: ; <<>> DiG 9.9.5-3ubuntu0.1-Ubuntu <<>> xkcd.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52538 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY:…
dayuloli
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Is low TTL an appreciable burden on DNS?

I currently work for an medium-sized institution whose DNS management is questionable at best. Often, there are DNS-related failures causing downtime for the entire building and our public-facing website. Though I am not directly in charge of the…
hexparrot
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DNS Nameserver updates affected by TTL? or is it just A records, MX etc?

The TTL has been set to 1H, so that IP changes for example.com can be made more quickly. The registrar has been configured with ns1.example.com and ns2.example.com, verified using WHOIS lookup. ns1 and ns2 are based in Texas. We're moving all of our…
700 Software
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How long does azure cdn live before updating

I am using the windows Azure CDN, And not like Amazon's one cannot configure any TTL regarding the files, I was wondering if there is any official document microsoft had regarding to the Time-to-live of the cdn content until it is being update ? Or…
Matan L
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What DNS Settings to use to migrate Domain from One Server to Another

I am going to migrate a site from one server to another. The site has a good bit of realtime transaction activity reading/writing to a backend database. I believe I should ratchet down the TTL in the DNS on the domain so that once I am ready to make…
H. Ferrence
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Allowing stale DNS results

Is there any method of allowing stale DNS results to be returned? By stale, I mean, where the TTL has expired, but no new record can be obtained, likely due to the nameserver being unavailable. To my knowledge, at least bind 9 doesn't have any…
Danny F
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How to find the initial values of TTL for your current operating system?

In this answer to a question related to interpreting the values of TTL from a ping operation it is said that the TTL values vary depending on the operating system. I understood more or less the purpose of TTL, which is basically used to prevent…
user236846
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Multiple $TTL statements in bind DNS zone file

I'm using a socks proxy to connect to servers using another application. The proxy, which runs on Solaris 10. The server hosting the proxy is configured to use our own internal DNS server (bind) to resolve internal hostnames. Sometimes, we need to…
Yanick Girouard
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bind9; how to automatically refresh entry after entry expires

I am looking for a way to automatically refresh entries in my cache if it expires. For example, example.com has a TTL of 60, i would like to automatically refresh it if it expires so that when users query example.com a fresh version is already in…
Susan
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Will setting my DNS TTL to 86400 prevent minor DNS outages from making my site unavailable?

This morning, Network Solutions (where we host our DNS) had some intermittent DNS Server outages. All of our sites were inaccessible during this time. When network solutions DNS Servers came back up, so did our sites. Our DNS TTLs are currently set…
Adam Balsam
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How to actually set max-age headers on Windows Server?

I've set the max age to 1 minute, but when I look at the response headers, I see max-age=86400 (one day). Is something else overriding this setting? I've also set the kernel cache to 1 minute for most mime types to make sure that's not the source.…
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Recommend a content delivery network (CDN) for a specific purpose

could you please recommend a CDN for the following use: 1) Ability to update files on the edge servers automatically through API, so it should take no more than 5-10 minutes to make a new version of a file available to all customers worldwide. I…
Alex
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Generating ICMP packets when TTL=2?

By inspecting the payload of ICMP time-exceeded packets, I noticed that sometimes it is the last but one router (when ttl=2 in the returned packet) or even a previous one(up to 5 hops before, ttl=5) that drops the packet and generates an ICMP…
Ricky Robinson
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Understanding how Tracert works

From what I gathered so far, Tracert works by sending 3 ICMP echo messages. Starting with a TTL value of 1. For each router the packet encounters, the TTL value will be decremented. For the 1st router, 1-1 = 0, so an ICMP "time exceeded" message…
iridescent
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Optimizing TTL values for DYNDNS service

I've finally gotten my own DYNDNS working but I am looking for some advice on optimizing it. Edit: Basiclly I got a Domain at a registrar that I point to my own nameservers where I keep my own records. I'm using nsupdate to update records. I want…
Thuy
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